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12th Standard Maths English Medium Reduced Syllabus Important Questions with Answer key - 2021 Part - 2

12th Standard

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Maths

Time : 02:45:00 Hrs
Total Marks : 165

      Multiple Choice Questions

    15 x 1 = 15
  1. If A = \(\left[ \begin{matrix} 2 & 0 \\ 1 & 5 \end{matrix} \right] \) and B = \(\left[ \begin{matrix} 1 & 4 \\ 2 & 0 \end{matrix} \right] \) then |adj (AB)| = 

    (a)

    -40

    (b)

    -80

    (c)

    -60

    (d)

    -20

  2. If ATA−1 is symmetric, then A2 =

    (a)

    A-1

    (b)

    (AT)2

    (c)

    AT

    (d)

    (A-1)2

  3. 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).
    (iv) A(adjA) = (adjA)A = |A| I

    (a)

    Only (i)

    (b)

    (ii) and (iii)

    (c)

    (iii) and (iv)

    (d)

    (i), (ii) and (iv)

  4. The area of the triangle formed by the complex numbers z, iz and z+iz in the Argand’s diagram is

    (a)

    \(\cfrac { 1 }{ 2 } \left| z \right| ^{ 2 }\)

    (b)

    |z|2

    (c)

    \(\cfrac { 3 }{ 2 } \left| z \right| ^{ 2 }\)

    (d)

    2|z|2

  5. The conjugate of a complex number is \(\cfrac { 1 }{ i-2 } \). Then the complex number is

    (a)

    \(\cfrac { 1 }{ i+2 } \)

    (b)

    \(\cfrac { -1 }{ i+2 } \)

    (c)

    \(\cfrac { -1 }{ i-2 } \)

    (d)

    \(\cfrac { 1 }{ i-2 } \)

  6. If z is a non zero complex number, such that 2iz2 = \(\bar { z } \) then |z| is

    (a)

    \(\cfrac { 1 }{ 2 } \)

    (b)

    1

    (c)

    2

    (d)

    3

  7. According to the rational root theorem, which number is not possible rational zero of 4x+ 2x- 10x- 5?

    (a)

    -1

    (b)

    \(\frac { 5 }{ 4 } \)

    (c)

    \(\frac { 4 }{ 5 } \)

    (d)

    5

  8. If a, b, c ∈ Q and p +√q (p, q ∈ Q) is an irrational root of ax2+bx+c = 0 then the other root is ___________

    (a)

    -p+√q

    (b)

    p-iq

    (c)

    p-√q

    (d)

    -p-√q

  9. Let a > 0, b > 0, c >0. Theh n both the root of the equation ax2+bx+c = 0 are _________

    (a)

    real and negative

    (b)

    real and positive

    (c)

    rational numbers

    (d)

    none

  10. A stone is thrown up vertically. The height it reaches at time t seconds is given by x = 80t -16t2. The stone reaches the maximum height in time t seconds is given by

    (a)

    2

    (b)

    2.5

    (c)

    3

    (d)

    3.5

  11. The maximum value of the function \(x^{2} e^{-2 x}, x>0\) is

    (a)

    \(\frac { 1 }{ e } \)

    (b)

    \(\frac { 1 }{ 2e } \)

    (c)

    \(\frac { 1 }{ { e }^{ 2 } } \)

    (d)

    \(\frac { 4 }{ { e }^{ 4 } } \)

  12. If f (x, y) = exy then \(\frac { { \partial }^{ 2 }f }{ \partial x\partial y } \) is equal to

    (a)

    xyexy

    (b)

    (1 +xy)exy

    (c)

    (1 +y)exy

    (d)

    (1 + x)exy

  13. If we measure the side of a cube to be 4 cm with an error of 0.1 cm, then the error in our calculation of the volume is

    (a)

    0.4 cu.cm

    (b)

    0.45 cu.cm

    (c)

    2 cu.cm

    (d)

    4.8 cu.cm

  14. If p and q are the order and degree of the differential equation \(y=\frac { dy }{ dx } +{ x }^{ 3 }\left( \frac { { d }^{ 2 }y }{ { dx }^{ 2 } } \right) +xy=cosx,\) When

    (a)

    p < q

    (b)

    p = q

    (c)

    p > q

    (d)

    p exists and q does not exist

  15. A binary operation * is defined on the set of positive rational numbers Q+ by a*b = \(\frac { ab }{ 4 } \). Then 3 * \(\left( \frac { 1 }{ 5 } *\frac { 1 }{ 2 } \right) \) is _____________

    (a)

    \(\frac { 3 }{ 160 } \)

    (b)

    \(\frac { 5 }{ 160 } \)

    (c)

    \(\frac { 3 }{ 10 } \)

    (d)

    \(\frac { 3 }{ 40 } \)

    1. 2 Marks

    15 x 2 = 30
  16. Find the modulus of the following complex numbers
    \(\frac { 2i }{ 3+4i } \)

  17. Find the modulus of the following complex numbers
    (1-i)10

  18. Find the modulus and principal argument of the following complex numbers.
    \(-\sqrt { 3 } +i\)

  19. Find the value of the complex number (i25)3.

  20. If α, β, γ  and \(\delta\) are the roots of the polynomial equation 2x+ 5x− 7x+ 8 = 0, find a quadratic equation with integer coefficients whose roots are α + β + γ + \(\delta\) and αβ૪\(\delta\).

  21. Find a polynomial equation of minimum degree with rational coefficients, having 2-\(\sqrt{3}\) as a root.

  22. Find a polynomial equation of minimum degree with rational coefficients, having 2i+3 as a root.

  23. Examine for the rational roots of x8- 3x + 1 = 0

  24. Find the eccentricity of the hyperbola with foci on the x-axis if the length of its conjugate axis is \({ \left( \frac { 3 }{ 4 } \right) }^{ th }\) of the length of its tranverse axis.

  25. Solve :\(\frac { dy }{ dx } =\frac { 2x }{ { x }^{ 2 }+1 } \)

    1. 3 Marks

    15 x 3 = 45
  26. Given the complex number z = 2 + 3i, represent the complex numbers in Argand diagram z, iz , and z+iz

  27. Given the complex number z = 2 + 3i, represent the complex numbers in Argand diagram z, −iz , and z−iz

  28. For the hyperbola 3x2 - 6y2 = -18, find the length of transverse and conjugate axes and eccentricity.

  29. Find the equation of the plane passing through the line of intersection of the planes \(\vec { r } .(2\hat { i } -7\hat { j } +4\hat { k } )=3\) and 3x - 5y + 11 = 0, and the point (-2, 1, 3)

  30. Find the equation of the plane which passes through the point (3, 4, -1) and is parallel to the plane 2x - 3y + 5z = 0. Also, find the distance between the two planes.

  31. Find the equation of the plane passing through the intersection of the planes \(\vec { r } .(\hat { i } +\hat { j } +\hat { k } )+1=0\) and \(\vec { r } .(2\hat { i } -3\hat { j } +5\hat { k } )=2\) and the point (-1, 2, 1).

  32. Find the absolute extrem of the following function on the given closed interval
    f(x) = x2 -12x + 10; [1, 2]

  33. A right circular cylinder has radius r =10 cm. and height h = 20 cm. Suppose that the radius of the cylinder is increased from 10 cm to 10. 1 cm and the height does not change. Estimate the change in the volume of the cylinder. Also, calculate the relative error and percentage error.

  34. Assuming log10e = 0.4343, find an approximate value of log10 1003

  35. Find the partial derivatives of the following functions at the indicated point
    h (x, y, z) = x sin (xy) + z2x, \(\left( 2,\frac { \pi }{ 4 }, 1\right) \) 

  36. A firm produces two types of calculators each week, x number of type A and y number of type B. The weekly revenue and cost functions (in rupees) are R(x, y) = 80x + 90y + 0.04xy − 0.05x2 − 0.05y2 and C(x, y) = 8x + 6y + 2000 respectively
    (i) Find the profit function P(x, y) 
    (ii) Find \(\frac { { \partial P } }{ \partial { x } } \) (1200, 1800) and \(\frac { \partial v }{ \partial y} \) (1200, 1800)

  37. Let U(x, y, z) = xyz, x = e-t, y = e-t cos t, z = sin t, t ∈ R. Find \(\frac{dU}{dt}\)

  38. Evaluate the following definite integrals:
    \(\int _{ 0 }^{ 1 }{ \sqrt { \frac { 1-x }{ 1+x } } } dx\)

    1. 5 Marks

    15 x 5 = 75
  39. For what value of λ, the system of equations x + y + z = 1, x + 2y + 4z = λ, x + 4y + 10z = λ2 is consistent.

  40. Find a polynomial equation of minimum degree with rational coefficients, having \(\sqrt{5}\)\(\sqrt{3}\) as a root.

  41. Find the domain of the following functions
    (i) f(x) = sin-1(2x - 3)
    (ii) f(x) = sin-1x + cos x

  42. Find the ratio of the area between the curves y=cosx and y=cos2x and x- axis from x=0 to \(x=\frac { \pi }{ 3 } \)

  43. Find the area bounded by the curve y2(2a-x)=x2 and the line x=2a.

  44. Solve : \({ e }^{ \frac { dy }{ dx } }=x+1,y(0)=5\)

  45. Solve :x2dy+y(x+y)dx=0 given that y=1 when x=1.

  46. Solve :\(x\frac { dy }{ dx } sin\left( \frac { y }{ x } \right) +x-ysin\left( y\frac { y }{ x } \right) =,y(1)=\frac { \pi }{ 2 } \)

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