Subject

Mathematics

Class

JEE Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

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71.

A square matrix [a0] in which a0 = 0 for i  j and a0 = k (constant) for i = j is callled a

  • unit matrix

  • scalar matrix

  • null matrix

  • diagonal matrix


B.

scalar matrix

We have, a0 = 0, i  jand          a0 = k, i = jIt is scalar matrix.


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72.

If A = 023- 4, hA = 03a2b24, then the values of h, a, b are respectively

  • - 6, - 12, - 18

  • - 6, 4, 9

  • - 6, - 4, - 9

  • - 6, + 12, 18


73.

If 1 - ii1 + 2i- i = x +iy, then x is equal to

  • - 2

  • - 1

  • 1

  • 2


74.

sec2tan - 12 + cosec2 cot - 13 is equal to 

  • 3

  • 10

  • 15

  • 20


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75.

sinh - 1x1 - x2 is equal to 

  • coth - 1x

  • sinh - 1x

  • - tanh - 1x

  • tanh - 1x


76.

If a = i^ + 4j^, b = 2i^ - 2j^, c = 5i^ + 9j^, then c is equal to

  • 2a + b

  • a + 2b

  • 3a + b

  • a + 3b


77.

ABCD is a parallelogram, with AC, BD as diagonals, then AC - BD is equal to

  • 4AB

  • AB

  • 3AB

  • 2AB


78.

If a = i^ + j^ + tk^, b = i^ + 2j^ + 3k^ then the values of 't' for which (a + b) and (a - b) are perpendicular, are

  • ± 2

  • ± 23

  • ±32

  • ± 3


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79.

If θ is the angle between a and b and a × b = a . b, then θ is equal to

  • 0

  • π

  • π2

  • π4


80.

i^ - j^, j^ - k^, k^ - i^ is equal to

  • 0

  • 1

  • 2

  • 3


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