If z1, z2 are two complex numbers satisfying z1 - 

Subject

Mathematics

Class

JEE Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

11.

If , then 16A + 9B is equal to

  • 4

  • 5

  • 6

  • 8


12.

The value of the series  + x55!logea5 + ... is

  • coshxlogea

  • cothxlogea

  • sinhxlogea

  • tanhxlogea


13.

Coefficient of x10 in the expansion of (2 + 3x)e- x is

  • - 2610!

  • - 2810!

  • - 3010!

  • - 3210!


14.

The set of all solutions of the inequation x2 - 2x + 5  0 in R is

  • R - - , - 5

  • R - 5, 

  • ϕ

  • R - - , - 4


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15.

If (x - 2) is a common factor of the expressions x2 + ax + b and x2 + cx + d, then, b - dc - a is equal to

  • - 2

  • - 1

  • 1

  • 2


16.

If the roots of the equation 4x3 - 12x2 + 11x + k = 0 are in arithmetic progression, then k is equal to

  • - 3

  • 1

  • 2

  • 3


17.

If f(x) is apolynomial ofdegreen with rational coefficients and 1 + 2i , 2 - 3 and 5 are three roots of f(x) = 0 , then the least value of n is

  • 5

  • 4

  • 3

  • 6


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18.

If z1, z2 are two complex numbers satisfying z1 - 3z23 - z1z2 = 1, z1  3, then z2 is equal to

  • 1

  • 2

  • 3

  • 4


A.

1

Given that, z1 - 3z23 - z1z2 = 1, z1  3 z1 - 3z2 = 3 - z1z2            z1z2 = z1z2 z1 - 3z22 = 3 - z1z22 z1 - 3z2z1 - 3z2 = 3 - z1z23 - z1z2 z12 - 3z1z2 - 3z1z2 + 9z22       = 9 - 3z1z2 - 3z1z2 + z12z22 9 - z121 - z22 = 0         z12 = 9 or z22 = 1          z1 = 3 or z2 = 1But, z1  3   z2 = 1


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19.

The value of n = 02i3n is

  • 9 + 6i13

  • 9 - 6i13

  • 9 + 6i

  • 9 - 6i


20.

If xn = cosπ2n + isinπ2n, then n = 1xn is equal to

  • - 1

  • 1

  • 12

  • - 3


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