If a + 2bcosxa - 2bcosy = a2&n

Subject

Mathematics

Class

JEE Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

11.

A survey shows that 63% of the peoplein a city read newspaper A whereas 76% read newspaper B. If x% of the people read both the newspapers, then a possible value of x can be :

  • 65

  • 55

  • 37

  • 29


12.

Two vertical poles AB = 15m and CD = 10m are standing apart on a horizontal ground with points A and C on the ground. If P is the point of intersection of BC and AD, then the height of P (in m) above the line AC is:

  • 10/3

  • 6

  • 5

  • 20/3


13.

Let [t] denote the greatest integer  t. Then the equation in x, [x]2 + 2[x + 2] – 7 = 0 has :

  • no integral solution

  • infinitely many solutions

  • exactly two solutions

  • exactly four integral solutions


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14.

If a + 2bcosxa - 2bcosy = a2 - b2, where a > b, then dxdy at π4, π4 is :

  • 2a + b2a - b

  • a + ba - b

  • a - ba + b

  • a - 2ba + 2b


B.

a + ba - b

a + 2bcosxa - 2bcosy = a2 - b2a - 2bcosy - 2bsinydxdy + 2bsinya + 2bcosx = 0dxdy = 2bsinya +2bcosx2bsinxa - 2bcosy = sinya +2bcosxsinxa - 2bcosydxdyπ4, π4 = a + ba - b


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15.

Let x0 be the point of local maxima of fx = a . b × c, where a = xi^ - 2j^ +3k^, b = - 2i^ + xj^ - k^ andc = 7i^ - 2j^ + xk^. Then the value of a . b + b . c + c . a at x = x0

is :

  • - 22

  • 14

  •  - 4

  •  - 30


16.

Let fx = x1 + x2dx x  0. Then f3 - f1 = ?

  • - π6 + 12 + 34

  • - π12 + 12 + 34

  • π12 + 12 - 34

  • π6 + 12 - 34


17.

Let f be the twice differential function on 1, 6. If f2 = 8, f'2 = 5,f'x  1 and f''x  4, for all x  1, 6, then :

  • f5 + f'5  28

  • f'5 + f''5  20

  • f5  10

  • f5 + f'5  26


 Multiple Choice QuestionsShort Answer Type

18.

Let 2x2 + 3x + 410 = r = 020 arxr. Then a7a13 = ?


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19.

Suppose a differentiable function f(x) satisfies the identity f(x + y) = f(x) + f(y) + xy2 + x2y, for all real x and y. If

limx0fxx = 1, then f'(3) is equal to :


20.

If the system of equations

x – 2y + 3z = 9

2x + y + z = b

x – 7y + az = 24,

has infinitely many solutions, then a – b is equal to :


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