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CBSE Class 12 Mathematics 2024 question paper (65/2)

Maximum marks 80 · Time 3 hours · 3 sets

Try each question first, then open its model answer. Where the paper offers a choice, both questions are shown with OR between them.

Section A

1 mark each

  1. Q.11 mark
    If the sum of all the elements of a 3×33 \times 3 scalar matrix is 9, then the product of all its elements is :

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  2. Q.21 mark
    Let f:R+→[−5,∞)f : R_+ \to [-5, \infty) be defined as f(x)=9x2+6x−5f(x) = 9x^2 + 6x - 5, where R+R_+ is the set of all non-negative real numbers. Then, f is :

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  3. Q.31 mark
    If ∣−abca−bcab−c∣=kabc\begin{vmatrix} -a & b & c \\ a & -b & c \\ a & b & -c \end{vmatrix} = kabc, then the value of k is :

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  4. Q.41 mark
    The number of points of discontinuity of f(x)={∣x∣+3,if x≤−3−2x,if −3<x<36x+2,if x≥3f(x) = \begin{cases} |x| + 3, & \text{if } x \le -3 \\ -2x, & \text{if } -3 < x < 3 \\ 6x + 2, & \text{if } x \ge 3 \end{cases} is :

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  5. Q.51 mark
    The function f(x)=x3−3x2+12x−18f(x) = x^3 - 3x^2 + 12x - 18 is :

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  6. Q.61 mark
    ∫0π/2sin⁡x−cos⁡x1+sin⁡xcos⁡x dx\displaystyle\int_0^{\pi/2} \dfrac{\sin x - \cos x}{1 + \sin x \cos x}\, dx is equal to :

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  7. Q.71 mark
    The differential equation dydx=F(x,y)\dfrac{dy}{dx} = F(x, y) will not be a homogeneous differential equation, if F(x, y) is :

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  8. Q.81 mark
    For any two vectors a⃗\vec{a} and b⃗\vec{b}, which of the following statements is always true ?

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  9. Q.91 mark
    The coordinates of the foot of the perpendicular drawn from the point (0, 1, 2) on the x-axis are given by :

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  10. Q.101 mark
    The common region determined by all the constraints of a linear programming problem is called :

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  11. Q.111 mark
    Let E be an event of a sample space S of an experiment, then P(S ∣ E)=P(S \,|\, E) =

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  12. Q.121 mark
    If A=[aij]A = [a_{ij}] be a 3×33 \times 3 matrix, where aij=i−3ja_{ij} = i - 3j, then which of the following is false ?

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  13. Q.131 mark
    The derivative of tan⁡−1(x2)\tan^{-1}(x^2) w.r.t. x is :

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  14. Q.141 mark
    The degree of the differential equation (y′′)2+(y′)3=xsin⁡(y′)(y'')^2 + (y')^3 = x \sin (y') is :

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  15. Q.151 mark
    The unit vector perpendicular to both vectors i^+k^\hat{i} + \hat{k} and i^−k^\hat{i} - \hat{k} is :

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  16. Q.161 mark
    Direction ratios of a vector parallel to line x−12=−y=2z+16\dfrac{x-1}{2} = -y = \dfrac{2z+1}{6} are :

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  17. Q.171 mark
    If F(x)=[cos⁡x−sin⁡x0sin⁡xcos⁡x0001]F(x) = \begin{bmatrix} \cos x & -\sin x & 0 \\ \sin x & \cos x & 0 \\ 0 & 0 & 1 \end{bmatrix} and [F(x)]2=F(kx)[F(x)]^2 = F(kx), then the value of k is :

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  18. Q.181 mark
    If a line makes an angle of 30∘30^\circ with the positive direction of x-axis, 120∘120^\circ with the positive direction of y-axis, then the angle which it makes with the positive direction of z-axis is :

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  19. Questions number 19 and 20 are Assertion and Reason based questions. Two statements are given, one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer from the codes (A), (B), (C) and (D) as given below.
    Q.191 mark
    Assertion (A) : For any symmetric matrix A, B'AB is a skew-symmetric matrix. Reason (R) : A square matrix P is skew-symmetric if P′=−PP' = -P.

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  20. Q.201 mark
    Assertion (A) : For two non-zero vectors a⃗\vec{a} and b⃗\vec{b}, a⃗⋅b⃗=b⃗⋅a⃗\vec{a} \cdot \vec{b} = \vec{b} \cdot \vec{a}. Reason (R) : For two non-zero vectors a⃗\vec{a} and b⃗\vec{b}, a⃗×b⃗=b⃗×a⃗\vec{a} \times \vec{b} = \vec{b} \times \vec{a}.

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Section B

2 marks each

  1. Q.21 (a)2 marks
    Find the value of tan⁡−1(−13)+cot⁡−1(13)+tan⁡−1[sin⁡(−π2)]\tan^{-1}\left(-\dfrac{1}{\sqrt{3}}\right) + \cot^{-1}\left(\dfrac{1}{\sqrt{3}}\right) + \tan^{-1}\left[\sin\left(-\dfrac{\pi}{2}\right)\right].
  2. OR

    Q.21 (b)2 marks
    Find the domain of the function f(x)=sin⁡−1(x2−4)f(x) = \sin^{-1}(x^2 - 4). Also, find its range.
  3. Q.22 (a)2 marks
    If f(x)=∣tan⁡2x∣f(x) = |\tan 2x|, then find the value of f′(x)f'(x) at x=π3x = \dfrac{\pi}{3}.
  4. OR

    Q.22 (b)2 marks
    If y=cosec (cot⁡−1x)y = \text{cosec}\,(\cot^{-1} x), then prove that 1+x2 dydx−x=0\sqrt{1 + x^2}\ \dfrac{dy}{dx} - x = 0.
  5. Q.232 marks
    If M and m denote the local maximum and local minimum values of the function f(x)=x+1xf(x) = x + \dfrac{1}{x} (x≠0)(x \ne 0) respectively, find the value of (M−m)(M - m).
  6. Q.242 marks
    Find : ∫e4x−1e4x+1 dx\displaystyle\int \dfrac{e^{4x} - 1}{e^{4x} + 1}\, dx
  7. Q.252 marks
    Show that f(x)=ex−e−x+x−tan⁡−1xf(x) = e^x - e^{-x} + x - \tan^{-1} x is strictly increasing in its domain.

Section C

3 marks each

  1. Q.26 (a)3 marks
    If x=ecos⁡3tx = e^{\cos 3t} and y=esin⁡3ty = e^{\sin 3t}, prove that dydx=−ylog⁡xxlog⁡y\dfrac{dy}{dx} = -\dfrac{y \log x}{x \log y}.
  2. OR

    Q.26 (b)3 marks
    Show that : ddx(∣x∣)=x∣x∣,x≠0\dfrac{d}{dx}\big(|x|\big) = \dfrac{x}{|x|}, x \ne 0
  3. Q.27 (a)3 marks
    Evaluate : ∫−222−x2+x dx\displaystyle\int_{-2}^{2} \sqrt{\dfrac{2 - x}{2 + x}}\, dx
  4. OR

    Q.27 (b)3 marks
    Find : ∫1x [(log⁡x)2−3log⁡x−4] dx\displaystyle\int \dfrac{1}{x\,[(\log x)^2 - 3 \log x - 4]}\, dx
  5. Q.28 (a)3 marks
    Find the particular solution of the differential equation given by 2xy+y2−2x2dydx=02xy + y^2 - 2x^2 \dfrac{dy}{dx} = 0; y=2y = 2, when x=1x = 1.
  6. OR

    Q.28 (b)3 marks
    Find the general solution of the differential equation : y dx=(x+2y2) dyy\, dx = (x + 2y^2)\, dy
  7. Q.293 marks
    The position vectors of vertices of Δ\Delta ABC are A(2i^−j^+k^)A(2\hat{i} - \hat{j} + \hat{k}), B(i^−3j^−5k^)B(\hat{i} - 3\hat{j} - 5\hat{k}) and C(3i^−4j^−4k^)C(3\hat{i} - 4\hat{j} - 4\hat{k}). Find all the angles of Δ\Delta ABC.
  8. Q.303 marks
    A pair of dice is thrown simultaneously. If X denotes the absolute difference of the numbers appearing on top of the dice, then find the probability distribution of X.
  9. Q.313 marks
    Find : ∫x2⋅sin⁡−1(x3/2) dx\displaystyle\int x^2 \cdot \sin^{-1}(x^{3/2})\, dx

Section D

5 marks each

  1. Q.32 (a)5 marks
    Show that a function f:R→Rf : R \to R defined by f(x)=2x1+x2f(x) = \dfrac{2x}{1 + x^2} is neither one-one nor onto. Further, find set A so that the given function f:R→Af : R \to A becomes an onto function.
  2. OR

    Q.32 (b)5 marks
    A relation R is defined on N×NN \times N (where N is the set of natural numbers) as : (a,b) R (c,d)⇔a−c=b−d(a, b)\ R\ (c, d) \Leftrightarrow a - c = b - d Show that R is an equivalence relation.
  3. Q.335 marks
    Find the equation of the line which bisects the line segment joining points A(2, 3, 4) and B(4, 5, 8) and is perpendicular to the lines x−83=y+19−16=z−107\dfrac{x-8}{3} = \dfrac{y+19}{-16} = \dfrac{z-10}{7} and x−153=y−298=z−5−5\dfrac{x-15}{3} = \dfrac{y-29}{8} = \dfrac{z-5}{-5}.
  4. Q.34 (a)5 marks
    Solve the following system of equations, using matrices : 2x+3y+10z=4\dfrac{2}{x} + \dfrac{3}{y} + \dfrac{10}{z} = 4, 4x−6y+5z=1\dfrac{4}{x} - \dfrac{6}{y} + \dfrac{5}{z} = 1, 6x+9y−20z=2\dfrac{6}{x} + \dfrac{9}{y} - \dfrac{20}{z} = 2 where x,y,z≠0x, y, z \ne 0
  5. OR

    Q.34 (b)5 marks
    If A=[1cot⁡x−cot⁡x1]A = \begin{bmatrix} 1 & \cot x \\ -\cot x & 1 \end{bmatrix}, show that A′A−1=[−cos⁡2x−sin⁡2xsin⁡2x−cos⁡2x]A'A^{-1} = \begin{bmatrix} -\cos 2x & -\sin 2x \\ \sin 2x & -\cos 2x \end{bmatrix}.
  6. Q.355 marks
    If A1A_1 denotes the area of region bounded by y2=4xy^2 = 4x, x=1x = 1 and x-axis in the first quadrant and A2A_2 denotes the area of region bounded by y2=4xy^2 = 4x, x=4x = 4, find A1:A2A_1 : A_2.

Section E

  1. Overspeeding increases fuel consumption and decreases fuel economy as a result of tyre rolling friction and air resistance. While vehicles reach optimal fuel economy at different speeds, fuel mileage usually decreases rapidly at speeds above 80 km/h. The relation between fuel consumption F (l/100 km) and speed V (km/h) under some constraints is given as F=V2500−V4+14F = \dfrac{V^2}{500} - \dfrac{V}{4} + 14. On the basis of the above information, answer the following questions :
    Q.36 (i)1 mark
    Find F, when V = 40 km/h.
  2. Q.36 (ii)1 mark
    Find dFdV\dfrac{dF}{dV}.
  3. Q.36 (iii) (a)2 marks
    Find the speed V for which fuel consumption F is minimum.
  4. OR

    Q.36 (iii) (b)2 marks
    Find the quantity of fuel required to travel 600 km at the speed V at which dFdV=−0⋅01\dfrac{dF}{dV} = -0{\cdot}01.
  5. The month of September is celebrated as the Rashtriya Poshan Maah across the country. Following a healthy and well-balanced diet is crucial in order to supply the body with the proper nutrients it needs. A balanced diet also keeps us mentally fit and promotes improved level of energy. A dietician wishes to minimize the cost of a diet involving two types of foods, food X (x kg) and food Y (y kg) which are available at the rate of ₹ 16/kg and ₹ 20/kg respectively. The feasible region satisfying the constraints is shown in Figure-2. On the basis of the above information, answer the following questions :
    Q.37 (i)2 marks
    Identify and write all the constraints which determine the given feasible region in Figure-2.
  6. Q.37 (ii)2 marks
    If the objective is to minimize cost Z=16x+20yZ = 16x + 20y, find the values of x and y at which cost is minimum. Also, find minimum cost assuming that minimum cost is possible for the given unbounded region.
  7. Airplanes are by far the safest mode of transportation when the number of transported passengers are measured against personal injuries and fatality totals. Previous records state that the probability of an airplane crash is 0⋅00001%0{\cdot}00001\%. Further, there are 95% chances that there will be survivors after a plane crash. Assume that in case of no crash, all travellers survive. Let E1E_1 be the event that there is a plane crash and E2E_2 be the event that there is no crash. Let A be the event that passengers survive after the journey. On the basis of the above information, answer the following questions :
    Q.38 (i)1 mark
    Find the probability that the airplane will not crash.
  8. Q.38 (ii)1 mark
    Find P(A ∣ E1)+P(A ∣ E2)P(A \,|\, E_1) + P(A \,|\, E_2).
  9. Q.38 (iii) (a)2 marks
    Find P(A).
  10. OR

    Q.38 (iii) (b)2 marks
    Find P(E2 ∣ A)P(E_2 \,|\, A).