#### 12th Standard Maths English Medium Free Online Test Book Back 1 Mark Questions with Answer Key

12th Standard

Reg.No. :
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Maths

Time : 00:10:00 Hrs
Total Marks : 10

10 x 1 = 10
1. If A$\left[ \begin{matrix} 1 & -2 \\ 1 & 4 \end{matrix} \right] =\left[ \begin{matrix} 6 & 0 \\ 0 & 6 \end{matrix} \right]$, then A =

(a)

$\left[ \begin{matrix} 1 & -2 \\ 1 & 4 \end{matrix} \right]$

(b)

$\left[ \begin{matrix} 1 & 2 \\ -1 & 4 \end{matrix} \right]$

(c)

$\left[ \begin{matrix} 4 & 2 \\ -1 & 1 \end{matrix} \right]$

(d)

$\left[ \begin{matrix} 4 & -1 \\ 2 & 1 \end{matrix} \right]$

2. Which of the following is/are correct?
(i) Adjoint of a symmetric matrix is also a symmetric matrix.
(ii) Adjoint of a diagonal matrix is also a diagonal matrix.
(iii) If A is a square matrix of order n and λ is a scalar, then adj(λA) = λn adj(A).

(a)

Only (i)

(b)

(ii) and (iii)

(c)

(iii) and (iv)

(d)

(i), (ii) and (iv)

3. The polynomial x3-kx2+9x has three real zeros if and only if, k satisfies

(a)

|k|≤6

(b)

k=0

(c)

|k|>6

(d)

|k|≥6

4. ${ tan }^{ -1 }\left( \frac { 1 }{ 4 } \right) +{ tan }^{ -1 }\left( \frac { 2 }{ 3 } \right)$is equal to

(a)

$\frac { 1 }{ 2 } { cos }^{ -1 }\left( \frac { 3 }{ 5 } \right)$

(b)

$\frac { 1 }{ 2 } { sin }^{ -1 }\left( \frac { 3 }{ 5 } \right)$

(c)

$\frac { 1 }{ 2 } {tan }^{ -1 }\left( \frac { 3 }{ 5 } \right)$

(d)

${ tan}^{ -1 }\left( \frac { 1}{ 2 } \right)$

5. The centre of the circle inscribed in a square formed by the lines x2−8x−12=0 and y2−14y+45 = 0 is

(a)

(4,7)

(b)

(7,4)

(c)

(9,4)

(d)

(4,9)

6. The eccentricity of the ellipse (x−3)2 +(y−4)2 =$\frac { { y }^{ 2 } }{ 9 }$ is

(a)

$\frac { \sqrt { 3 } }{ 2 }$

(b)

$\frac { 1 }{ 3 }$

(c)

$\frac { 1 }{ 3\sqrt { 2 } }$

(d)

$\frac { 1 }{ \sqrt { 3 } }$

7. If $\vec { a } ,\vec { b } ,\vec { c }$ are non-coplanar, non-zero vectors such that $[\vec { a } ,\vec { b } ,\vec { c } ]$ = 3, then ${ \{ [\vec { a } \times \vec { b } ,\vec { b } \times \vec { c } ,\vec { c } \times \vec { a } }]\} ^{ 2 }$ is equal to

(a)

81

(b)

9

(c)

27

(d)

18

8. A balloon rises straight up at 10 m/s. An observer is 40 m away from the spot where the balloon left the ground. Find the rate of change of the balloon's angle of elevation in radian per second when the balloon is 30 metres above the ground.

(a)

$\cfrac { 3 }{ 25 } radians/sec$

(b)

$\cfrac { 4 }{ 25 } radians/sec$

(c)

$\cfrac { 1 }{ 5 } radians/sec$

(d)

$\cfrac { 1 }{ 3 } radians/sec$

9. If v (x, y) = log (ex + ev), then $\frac { { \partial }v }{ \partial x } +\frac { \partial v }{ \partial y }$ is equal to

(a)

ex + ey

(b)

$\frac{1}{e^x + e^y}$

(c)

2

(d)

1

10. On a multiple-choice exam with 3 possible destructives for each of the 5 questions, the probability that a student will get 4 or more correct answers just by guessing is

(a)

$\cfrac { 11 }{ 243 }$

(b)

$\cfrac { 3 }{ 8 }$

(c)

$\cfrac { 1 }{ 243 }$

(d)

$\cfrac { 5 }{ 243 }$