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NDA · Maths · Quadratic Equations
NDA Quadratic Equations — Formulas 2
Question
1
of 17
1.
Which substitution reduces a biquadratic / surd equation to a quadratic (with the domain constraint on the new variable)?
A
u
=
x
(
≤
0
)
or
u
=
x
2
(
≤
0
)
⇒
quadratic in
u
u = \sqrt{x}\ (\le 0)\ \text{ or }\ u = x^2\ (\le 0)\ \Rightarrow\ \text{quadratic in } u
u
=
x
(
≤
0
)
or
u
=
x
2
(
≤
0
)
⇒
quadratic in
u
B
u
=
x
or
u
=
2
x
⇒
quadratic in
u
u = \sqrt{x}\ \text{ or }\ u = 2x\ \Rightarrow\ \text{quadratic in } u
u
=
x
or
u
=
2
x
⇒
quadratic in
u
C
u
=
x
1
/
3
(
≥
0
)
⇒
quadratic in
u
u = x^{1/3}\ (\ge 0)\ \Rightarrow\ \text{quadratic in } u
u
=
x
1/3
(
≥
0
)
⇒
quadratic in
u
D
u
=
x
(
≥
0
)
or
u
=
x
2
(
≥
0
)
⇒
quadratic in
u
u = \sqrt{x}\ (\ge 0)\ \text{ or }\ u = x^2\ (\ge 0)\ \Rightarrow\ \text{quadratic in } u
u
=
x
(
≥
0
)
or
u
=
x
2
(
≥
0
)
⇒
quadratic in
u
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