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NDA 2020 (Combined I & II), Paper I, Mathematics question paper

120 questions · 300 marks · 150 minutes · +2.5 per correct answer, -0.83 per wrong one

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  1. 1
    If matrix A=(1−ii−i1−i)A = \begin{pmatrix} 1-i & i \\ -i & 1-i \end{pmatrix} where i=−1i = \sqrt{-1}, then which one of the following is correct?

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  2. 2
    The term independent of xx in the binomial expansion of (2x2−x)10\left(\frac{2}{x^2} - \sqrt{x}\right)^{10} is equal to

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  3. 3
    If (1+2x−x2)6=a0+a1x+a2x2+…+a12x12(1+2x-x^2)^6 = a_0 + a_1x + a_2x^2 + \ldots + a_{12}x^{12}, then what is a0−a1+a2−a3+a4−…+a12a_0 - a_1 + a_2 - a_3 + a_4 - \ldots + a_{12} equal to?

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  4. 4
    If C(20,n+2)=C(20,n−2)C(20, n+2) = C(20, n-2), then what is nn equal to?

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  5. 5
    For how many values of kk, is the matrix (0k4−k0−5−kk−1)\begin{pmatrix}0 & k & 4 \\ -k & 0 & -5 \\ -k & k & -1\end{pmatrix} singular?

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  6. 6
    The number (1101101+1011011)2(1101101 + 1011011)_2 can be written in decimal system as

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  7. 7
    What is the value of 110log⁡51024−log⁡510+15log⁡53125\frac{1}{10}\log_5 1024 - \log_5 10 + \frac{1}{5}\log_5 3125?

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  8. 8
    If x=log⁡c(ab)x = \log_c(ab), y=log⁡a(bc)y = \log_a(bc), z=log⁡b(ca)z = \log_b(ca), then which of the following is correct?

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  9. 9
    Let A=(x+yy2xx−y)A = \begin{pmatrix}x+y & y \\ 2x & x-y\end{pmatrix}, B=(2−1)B = \begin{pmatrix}2 \\ -1\end{pmatrix} and C=(32)C = \begin{pmatrix}3 \\ 2\end{pmatrix}. If AB=CAB = C, then what is the value of the determinant of the matrix AA?

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  10. 10
    If 1.5≤x≤4.51.5 \leq x \leq 4.5, then which one of the following is correct?

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  11. 11
    Let S={1,2,3,…}S=\{1,2,3,\ldots\}. A relation RR on S×SS\times S is defined by xRyxRy if log⁡ax>log⁡ay\log_a x > \log_a y when a=12a=\frac{1}{2}. Then the relation is

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  12. 12
    What is the value of the determinant ∣ii2i3i4i6i8i9i12i15∣\begin{vmatrix}i & i^2 & i^3 \\ i^4 & i^6 & i^8 \\ i^9 & i^{12} & i^{15}\end{vmatrix} where i=−1i=\sqrt{-1}?

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  13. 13
    Let A=(ahghbfgfc)A = \begin{pmatrix}a & h & g \\ h & b & f \\ g & f & c\end{pmatrix} and B=(xyz)B = \begin{pmatrix}x \\ y \\ z\end{pmatrix}, then what is ABAB equal to?

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  14. 14
    What is the number of ways in which the letters of the word 'ABLE' can be arranged so that the vowels occupy even places?

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  15. 15
    What is the maximum number of points of intersection of 5 non-overlapping circles?

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  16. Directions for the following three (03) items: Consider the following Venn diagram, where X, Y and Z are three sets. Let the number of elements in Z be denoted by n(Z) which is equal to 90.
    16
    If the number of elements in Y and Z are in the ratio 4 : 5, then what is the value of b?

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  17. 17
    What is the value of n(X)+n(Y)+n(Z)−n(X∩Y)−n(Y∩Z)−n(X∩Z)+n(X∩Y∩Z)n(X)+n(Y)+n(Z)-n(X\cap Y)-n(Y\cap Z)-n(X\cap Z)+n(X\cap Y\cap Z)?

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  18. 18
    If the number of elements belonging to neither X, nor Y, nor Z is equal to p, then what is the number of elements in the complement of X?

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  19. Directions for the following two (02) items: Read the following information and answer the two items that follow: Let tan⁡3Atan⁡A=K\frac{\tan 3A}{\tan A} = K, where tan⁡A≠0\tan A \neq 0 and K≠13K \neq \frac{1}{3}.
    19
    What is tan⁡2A\tan^2 A equal to?

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  20. 20
    For real values of tan⁡A\tan A, KK cannot\textbf{\text{cannot}} lie between

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  21. Directions for the following two (02) items: Read the following information and answer the two items that follow: ABCD is a trapezium such that AB and CD are parallel and BC is perpendicular to them. Let ∠ADB = θ, ∠ABD = α, BC = p and CD = q.
    21
    Consider the following: 1. ADsin⁡θ=ABsin⁡αAD\sin\theta = AB\sin\alpha 2. BDsin⁡θ=ABsin⁡(θ+α)BD\sin\theta = AB\sin(\theta+\alpha). Which of the above is/are correct?

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  22. 22
    What is AB equal to?

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  23. 23
    If tan⁡θ=cos⁡17°−sin⁡17°cos⁡17°+sin⁡17°\tan\theta=\frac{\cos 17°-\sin 17°}{\cos 17°+\sin 17°}, then what is the value of θ\theta?

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  24. 24
    A and B are positive acute angles such that cos⁡2B=3sin⁡2A\cos 2B = 3\sin^2 A and 3sin⁡2A=2sin⁡2B3\sin 2A = 2\sin 2B. What is the value of (A+2B)(A+2B)?

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  25. 25
    What is sin⁡3x+cos⁡3x+4sin⁡3x−3sin⁡x+3cos⁡x−4cos⁡3x\sin 3x + \cos 3x + 4\sin^3 x - 3\sin x + 3\cos x - 4\cos^3 x equal to?

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  26. 26
    The value of ordinate of the graph of y=2+cos⁡xy = 2 + \cos x lies in the interval

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  27. 27
    What is the value of 8cos⁡10°⋅cos⁡20°⋅cos⁡40°8\cos 10°\cdot\cos 20°\cdot\cos 40°?

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  28. 28
    What is the value of cos⁡48°−cos⁡12°\cos 48°-\cos 12°?

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  29. 29
    Consider the following statements: 1. If ABC is a right-angled triangle, right-angled at A and if sin⁡B=13\sin B=\frac{1}{3}, then csc⁡C=3\csc C=3. 2. If bcos⁡B=ccos⁡Cb\cos B=c\cos C and if the triangle ABC is not right-angled, then ABC must be isosceles. Which of the above statements is/are correct?

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  30. 30
    Consider the following statements: 1. If in a triangle ABC, A=2BA=2B and b=cb=c, then it must be an obtuse-angled triangle. 2. There exists no triangle ABC with A=40°A=40°, B=65°B=65° and ac=sin⁡40°csc⁡15°\frac{a}{c}=\sin 40°\csc 15°. Which of the above statements is/are correct?

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  31. Directions for the following three (03) items: Read the following information and answer the three items that follow: Let asin⁡2x+bcos⁡2x=ca\sin^2 x + b\cos^2 x = c; bsin⁡2y+acos⁡2y=db\sin^2 y + a\cos^2 y = d and ptan⁡x=qtan⁡yp\tan x = q\tan y.
    31
    What is tan⁡2x\tan^2 x equal to?

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  32. 32
    What is d−ab−d\frac{d-a}{b-d} equal to?

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  33. 33
    What is p2q2\frac{p^2}{q^2} equal to?

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  34. Directions for the following three (03) items: Read the following information and answer the three items that follow: Let tn=sin⁡nθ+cos⁡nθt_n = \sin^n\theta + \cos^n\theta.
    34
    What is t3−t5t5−t7\frac{t_3-t_5}{t_5-t_7} equal to?

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  35. 35
    What is t12−t2t_1^2 - t_2 equal to?

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  36. 36
    What is the value of t10t_{10} where θ=45°\theta=45°?

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  37. Directions for the following three (03) items: Read the following information and answer the three items that follow: Let α=β=15°\alpha = \beta = 15°.
    37
    What is the value of sin⁡α+cos⁡β\sin\alpha + \cos\beta?

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  38. 38
    What is the value of sin⁡7α−cos⁡7β\sin 7\alpha - \cos 7\beta?

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  39. 39
    What is sin⁡(α+1°)+cos⁡(β+1°)\sin(\alpha+1°)+\cos(\beta+1°) equal to?

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  40. 40
    If sin⁡x+sin⁡y=cos⁡y−cos⁡x\sin x+\sin y=\cos y-\cos x, where 0<y<x<π20<y<x<\frac{\pi}{2}, then what is tan⁡(x−y2)\tan\left(\frac{x-y}{2}\right) equal to?

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  41. 41
    If AA is a matrix of order 3×53\times5 and BB is a matrix of order 5×35\times3, then the order of ABAB and BABA will respectively be

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  42. 42
    If p2p^2, q2q^2 and r2r^2 (where p,q,r>0p,q,r>0) are in GP, then which of the following is/are correct? 1. pp, qq and rr are in GP. 2. ln⁡p\ln p, ln⁡q\ln q and ln⁡r\ln r are in AP. Select the correct answer using the code given below:

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  43. 43
    If cot⁡α\cot\alpha and cot⁡β\cot\beta are the roots of the equation x2−3x+2=0x^2-3x+2=0, then what is cot⁡(α+β)\cot(\alpha+\beta) equal to?

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  44. 44
    The roots α\alpha and β\beta of a quadratic equation satisfy the relations α+β=α2+β2\alpha+\beta=\alpha^2+\beta^2 and αβ=α2β2\alpha\beta=\alpha^2\beta^2. What is the number of such quadratic equations?

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  45. 45
    What is the argument of the complex number 1−i31+i3\frac{1-i\sqrt{3}}{1+i\sqrt{3}}, where i=−1i=\sqrt{-1}?

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  46. 46
    What is the modulus of the complex number cos⁡θ+isin⁡θcos⁡θ−isin⁡θ\frac{\cos\theta+i\sin\theta}{\cos\theta-i\sin\theta}, where i=−1i=\sqrt{-1}?

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  47. 47
    Consider the proper subsets of {1,2,3,4}\{1,2,3,4\}. How many of these proper subsets are superset of the set {3}\{3\}?

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  48. 48
    Let pp, qq and rr be three distinct positive real numbers. If D=∣pqrqrprpq∣D = \begin{vmatrix}p & q & r \\ q & r & p \\ r & p & q\end{vmatrix}, then which one of the following is correct?

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  49. 49
    What is the sum of the last five coefficients in the expansion of (1+x)9(1+x)^9 when it is expanded in ascending powers of xx?

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  50. 50
    Consider the following in respect of a non-singular matrix of order 3: 1. A(adj A)=(adj A)AA(\text{adj }A)=(\text{adj }A)A 2. ∣adj A∣=∣A∣|\text{adj }A|=|A|. Which of the above statements is/are correct?

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  51. 51
    The center of the circle (x−2a)(x−2b)+(y−2c)(y−2d)=0(x-2a)(x-2b)+(y-2c)(y-2d)=0 is

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  52. 52
    The point (1,−1)(1,-1) is one of the vertices of a square. If 3x+2y=53x+2y=5 is the equation of one diagonal of the square, then what is the equation of the other diagonal?

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  53. 53
    Let P(x,y)P(x,y) be any point on the ellipse 25x2+16y2=40025x^2+16y^2=400. If Q(0,3)Q(0,3) and R(0,−3)R(0,-3) are two points, then what is (PQ+PR)(PQ+PR) equal to?

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  54. 54
    If the circumcentre of the triangle formed by the lines x+2=0x+2=0, y+2=0y+2=0 and kx+y+2=0kx+y+2=0 is (−1,−1)(-1,-1), then what is the value of kk?

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  55. 55
    In the parabola y2=xy^2=x, what is the length of the chord passing through the vertex and inclined to the x-axis at an angle θ\theta?

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  56. 56
    Under which condition, are the points (a,b)(a,b), (c,d)(c,d) and (a−c,b−d)(a-c,b-d) collinear?

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  57. 57
    Let ABC be a triangle. If D(2,5)D(2,5) and E(5,9)E(5,9) are the mid-points of the sides AB and AC respectively, then what is the length of the side BC?

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  58. 58
    If the foot of the perpendicular drawn from the point (0,k)(0,k) to the line 3x−4y−5=03x-4y-5=0 is (3,1)(3,1), then what is the value of kk?

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  59. 59
    What is the obtuse angle between the lines whose slopes are 2−32-\sqrt{3} and 2+32+\sqrt{3}?

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  60. 60
    If 3x−4y−5=03x-4y-5=0 and 3x−4y+15=03x-4y+15=0 are the equations of a pair of opposite sides of a square, then what is the area of the square?

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  61. 61
    What is the length of the diameter of the sphere whose centre is at (1,−2,3)(1,-2,3) and which touches the plane 6x−3y+2z−4=06x-3y+2z-4=0?

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  62. 62
    What is the perpendicular distance from the point (2,3,4)(2,3,4) to the line x−01=y−00=z−00\frac{x-0}{1}=\frac{y-0}{0}=\frac{z-0}{0}?

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  63. 63
    If a line has direction ratios ⟨a+b,b+c,c+a⟩\langle a+b, b+c, c+a\rangle, then what is the sum of the squares of its direction cosines?

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  64. 64
    Into how many compartments do the coordinate planes divide the space?

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  65. 65
    What is the equation of the plane which cuts an intercept 5 units on the z-axis and is parallel to xy-plane?

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  66. 66
    If a^\hat{a} is a unit vector in the xy-plane making an angle 30°30° with the positive x-axis, then what is a^\hat{a} equal to?

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  67. 67
    Let A be a point in space such that ∣OA→∣=12|\overrightarrow{OA}|=12, where O is the origin. If OA→\overrightarrow{OA} is inclined at angles 45°45° and 60°60° with x-axis and y-axis respectively, then what is OA→\overrightarrow{OA} equal to?

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  68. 68
    Two adjacent sides of a parallelogram are 2i^−4j^+5k^2\hat{i}-4\hat{j}+5\hat{k} and i^−2j^−3k^\hat{i}-2\hat{j}-3\hat{k}. What is the magnitude of dot product of vectors which represent its diagonals?

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  69. 69
    If ∣a⃗×b⃗∣2+∣a⃗⋅b⃗∣2=144|\vec{a}\times\vec{b}|^2+|\vec{a}\cdot\vec{b}|^2=144 and ∣a⃗∣=4|\vec{a}|=4, then what is ∣b⃗∣|\vec{b}| equal to?

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  70. 70
    If the vectors a⃗=2i^−3j^+k^\vec{a}=2\hat{i}-3\hat{j}+\hat{k}, b⃗=i^+2j^−3k^\vec{b}=\hat{i}+2\hat{j}-3\hat{k} and c⃗=j^+pk^\vec{c}=\hat{j}+p\hat{k} are coplanar, then what is the value of pp?

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  71. 71
    What is lim⁡x→1x+x2+x3−3x−1\lim_{x\to1}\frac{x+x^2+x^3-3}{x-1} equal to?

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  72. 72
    The radius of a circle is increasing at the rate of 0.70.7 cm/sec. What is the rate of increase of its circumference?

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  73. 73
    If lim⁡x→1x4−1x−1=lim⁡x→kx3−k3x2−k2\lim_{x\to1}\frac{x^4-1}{x-1}=\lim_{x\to k}\frac{x^3-k^3}{x^2-k^2}, where k≠0k\neq0, then what is the value of kk?

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  74. 74
    The order and degree of the differential equation kdydx=∫[1+(dydx)2]23dxk\frac{dy}{dx}=\int\left[1+\left(\frac{dy}{dx}\right)^2\right]^{\frac{2}{3}}dx are respectively

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  75. 75
    What is lim⁡x→0sin⁡xlog⁡(1−x)x2\lim_{x\to0}\frac{\sin x\log(1-x)}{x^2} equal to?

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  76. 76
    If f(x)=3x2−5x+pf(x)=3x^2-5x+p and f(0)f(0) and f(1)f(1) are opposite in sign, then which of the following is correct?

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  77. 77
    If eθφ=c+4θφe^{\theta\varphi}=c+4\theta\varphi, where cc is an arbitrary constant and φ\varphi is a function of θ\theta, then what is φ dθ\varphi\,d\theta equal to?

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  78. 78
    If p(x)=(4e)2xp(x)=(4e)^{2x}, then what is ∫p(x) dx\int p(x)\,dx equal to?

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  79. 79
    What is the value of ∫0π/4(tan⁡3x+tan⁡x) dx\int_0^{\pi/4}(\tan^3 x+\tan x)\,dx?

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  80. 80
    Let y=3x2+2y=3x^2+2. If xx changes from 10 to 10·1, then what is the total change in yy?

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  81. 81
    If f(x)=sin⁡xxf(x)=\frac{\sin x}{x}, where x∈Rx\in\mathbf{R}, is to be continuous at x=0x=0, then the value of the function at x=0x=0

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  82. 82
    The solution of the differential equation dy=(1+y2) dxdy=(1+y^2)\,dx is

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  83. 83
    What is ∫(elog⁡x+sin⁡x)cos⁡x dx\int(e^{\log x}+\sin x)\cos x\,dx equal to?

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  84. 84
    What is the domain of the function f(x)=cos⁡−1(x−2)f(x)=\cos^{-1}(x-2)?

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  85. 85
    What is the area of the region enclosed between the curve y2=2xy^2=2x and the straight line y=xy=x?

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  86. 86
    If f(x)=2x−x2f(x)=2x-x^2, then what is the value of f(x+2)+f(x−2)f(x+2)+f(x-2) when x=0x=0?

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  87. 87
    If xmyn=am+nx^m y^n=a^{m+n}, then what is dydx\frac{dy}{dx} equal to?

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  88. 88
    What is ∫dxx(xn+1)\int\frac{dx}{x(x^n+1)} equal to?

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  89. 89
    What is the minimum value of ∣x−1∣|x-1|, where x∈Rx\in\mathbb{R}?

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  90. 90
    What is the value of kk such that integration of 3x2+8−4kx\frac{3x^2+8-4k}{x} with respect to xx, may be a rational function?

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  91. 91
    Consider the following statements for f(x)=e−∣x∣f(x)=e^{-|x|}: 1. The function is continuous at x=0x=0. 2. The function is differentiable at x=0x=0. Which of the above statements is/are correct?

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  92. 92
    What is the maximum value of sin⁡x⋅cos⁡x\sin x\cdot\cos x?

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  93. 93
    What is lim⁡x→03x+3−x−2x\lim_{x\to0}\frac{3^x+3^{-x}-2}{x} equal to?

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  94. 94
    What is the derivative of tan⁡−1x\tan^{-1}x with respect to cot⁡−1x\cot^{-1}x?

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  95. 95
    The function u(x,y)=cu(x,y)=c which satisfies the differential equation x(dx−dy)+y(dy−dx)=0x(dx-dy)+y(dy-dx)=0 is

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  96. 96
    What is the minimum value of 3cos⁡(A+π3)3\cos\left(A+\frac{\pi}{3}\right) where A∈RA\in\mathbb{R}?

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  97. 97
    Consider the following statements: 1. The function f(x)=ln⁡xf(x)=\ln x increases in the interval (0,∞)(0,\infty). 2. The function f(x)=tan⁡xf(x)=\tan x increases in the interval (−π2,π2)\left(-\frac{\pi}{2},\frac{\pi}{2}\right). Which of the above statements is/are correct?

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  98. 98
    Which one of the following is correct in respect of the graph of y=1x−1y=\frac{1}{x-1}?

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  99. 99
    What is the solution of the differential equation ln⁡(dydx)=x\ln\left(\frac{dy}{dx}\right)=x?

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  100. 100
    Let ll be the length and bb be the breadth of a rectangle such that l+b=kl+b=k. What is the maximum area of the rectangle?

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  101. 101
    The numbers 4 and 9 have frequencies xx and (x−1)(x-1) respectively. If their arithmetic mean is 6, then what is the value of xx?

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  102. 102
    If three dice are rolled under the condition that no two dice show the same face, then what is the probability that one of the faces is having the number 6?

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  103. 103
    If P(A∪B)=56P(A\cup B)=\frac{5}{6}, P(A∩B)=13P(A\cap B)=\frac{1}{3} and P(not A)=12P(\text{not }A)=\frac{1}{2}, then which one of the following is not\textbf{\text{not}} correct?

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  104. 104
    The sum of deviations of nn number of observations measured from 2.52.5 is 50. The sum of deviations of the same set of observations measured from 3.53.5 is −50-50. What is the value of nn?

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  105. 105
    A data set of nn observations has mean 2M2M, while another data set of 2n2n observations has mean MM. What is the mean of the combined data sets?

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  106. Directions for the following three (03) items: Read the following information and answer the three items that follow:
    MarksPhysicsMathematics
    10-20810
    20-301121
    30-403038
    40-502615
    50-601510
    60-70106
    106
    The difference between number of students under Physics and Mathematics is largest for the interval

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  107. 107
    Consider the following statements: 1. Modal value of the marks in Physics lies in the interval 30−4030-40. 2. Median of the marks in Physics is less than that of marks in Mathematics. Which of the above statements is/are correct?

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  108. 108
    What is the mean of marks in Physics?

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  109. 109
    What is the standard deviation of the observations −6,−5,−4,−1,1,4,5,6-\sqrt{6}, -\sqrt{5}, -\sqrt{4}, -1, 1, \sqrt{4}, \sqrt{5}, \sqrt{6}?

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  110. 110
    If ∑xi=20\sum x_i=20, ∑xi2=200\sum x_i^2=200 and n=10n=10 for an observed variable xx, then what is the coefficient of variation?

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  111. 111
    What is the probability that February of a leap year selected at random, will have five Sundays?

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  112. 112
    The arithmetic mean of 100 observations is 40. Later, it was found that an observation '53' was wrongly read as '83'. What is the correct arithmetic mean?

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  113. 113
    A husband and wife appear in an interview for two vacancies for the same post. The probability of the husband's selection is 17\frac{1}{7} and that of the wife's selection is 15\frac{1}{5}. If the events are independent, then the probability of which one of the following is 1135\frac{11}{35}?

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  114. 114
    A dealer has a stock of 15 gold coins out of which 6 are counterfeits. A person randomly picks 4 of the 15 gold coins. What is the probability that all the coins picked will be counterfeits?

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  115. 115
    A committee of 3 is to be formed from a group of 2 boys and 2 girls. What is the probability that the committee consists of 2 boys and 1 girl?

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  116. 116
    In a lottery of 10 tickets numbered 1 to 10, two tickets are drawn simultaneously. What is the probability that both the tickets drawn have prime numbers?

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  117. 117
    Let X and Y represent prices (in ₹) of a commodity in Kolkata and Mumbai respectively. It is given that Xˉ=65\bar{X}=65, Yˉ=67\bar{Y}=67, σX=2.5\sigma_X=2.5, σY=3.5\sigma_Y=3.5 and r(X,Y)=0.8r(X,Y)=0.8. What is the equation of regression of Y on X?

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  118. 118
    Consider a random variable X which follows Binomial distribution with parameters n=10n=10 and p=15p=\frac{1}{5}. Then Y=10−XY=10-X follows Binomial distribution with parameters nn and pp respectively given by

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  119. 119
    If A and B are two events such that P(A)=0.6P(A)=0.6, P(B)=0.5P(B)=0.5 and P(A∩B)=0.4P(A\cap B)=0.4, then consider the following statements: 1. P(Aˉ∪B)=0.9P(\bar{A}\cup B)=0.9. 2. P(Bˉ∣Aˉ)=0.6P(\bar{B}\mid\bar{A})=0.6. Which of the above statements is/are correct?

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  120. 120
    Three cooks X, Y and Z bake a special kind of cake, and with respective probabilities 0·02, 0·03 and 0·05, it fails to rise. In the restaurant where they work, X bakes 50%, Y bakes 30% and Z bakes 20% of cakes. What is the proportion of failures caused by X?

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