If α, β, γ are the 

Subject

Mathematics

Class

JEE Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

11.

If , then A is equal to

  • - 150

  • - 825

  • 2725


12.

n = 12n2 + n + 1n! is equal to

  • 2e - 1

  • 2e + 1

  • 6e - 1

  • 6e + 1


13.

If a <1, b = k = 1akk, then a is equal to

  • k = 1- 1kbkk

  • k = 1- 1k - 1bkk!

  • k = 1- 1kbkk - 1!

  • k = 1- 1k - 1bkk + 1!


14.

E1 : a + b + c = 0, if 1 is a root of ax2 + bx + c = 0, E2 : b2 - a2 = 2ac, if sinθ, cosθ are the roots of ax2 + bx + c = 0 Which of the following is true ?

  • E1 is true, E2 is true

  • E1 is true, E2 is false

  • E1 is false, E2 is true

  • E1 is false, E2 is false


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15.

The roots of the equation x - 3x - 2 = 0 are

  • - 1, - 1, 2

  • - 1, 1, - 2

  • - 1, 2, - 3

  • - 1, - 1, - 2


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16.

If α, β, γ are the roots of x3 + 2x2 - 3x - 1 = 0 then α- 2 + β- 2 + γ- 2 = 

  • 12

  • 13

  • 14

  • 15


B.

13

Given that α, β, γ are the roots of equation x3 + 2x2 - 3x - 1 = 0       α + β + γ = - 2     ...i αβ + βγ + γα = - 3  ...iiand            αβγ = 1      ...iiiOn squaring equation ii, we get α2β 2+ β2γ2 + γ2α2 + 2αβγα + β + γ = 9 α2β 2+ β2γ2 + γ2α2 = 9 - 21- 2 = 13Now α- 2 + β- 2 + γ- 2 = α2β 2+ β2γ2 + γ2α2αβγ2 α- 2 + β- 2 + γ- 2  = 131 = 13


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17.

If A + C = 2B, then cosC - cosAsinA - sinC is equal to

  • cotB

  • cot2B

  • tan2B

  • tanB


18.

A + B = C  cos2A + cos2B + cos2C - 2cosAcosBcosC is equal to

  • 1

  • 2

  • 0

  • 3


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19.

If m- 3, 4 + n4 - 3 = 10 - 11, then 3m + 7n is equal to

  • 3

  • 5

  • 10

  • 1


20.

If cos2x = 2 + 1cosx - 12, cosx  12 then x 

  • 2 ± π3 : n  Z

  • 2 ± π6 : n  Z

  • 2 ± π2 : n  Z

  • 2 ± π4 : n  Z


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