Subject

Mathematics

Class

JEE Class 12

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 Multiple Choice QuestionsShort Answer Type

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81.

The harmonic mean of two numbers is 4. Their arithmetic mean A and geometric mean G satisfy the relation 2A +G2 = 27. Find the numbers.


Given, HM = 4

 AM × HM= GM2 A × A = G2  G2 = 4A

But it is given 2A + G2 = 27

 2A + 4A = 27  6A = 27            A = 92and        G2 = 18  a + b2 = 92 and ab = 18  a + b = 9 and ab = 18         a = 6, b = 3, b = 6


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82.

Find the image of the point (- 8, 12) with respect to the line 4x + 7y + 13 = 0.


83.

How many triangles can be formed by joining 6 points lying on a circle?


84.

If r2 = x2 + y2 + z2, then prove that


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85.

Determine the sum of imaginary roots of the equation (2x + x - 1) ( 4x2 + 2x - 3) = 6


86.

If cos(A) + cos(B) + cos(C) = 0, prove that
cos(3A) + cos(3B) + cos(3C) = 12 cos(A) cos(B)cos(C)


87.

If the area of a rectangle is 64 sq unit, find the minimum value possible for its perimeter


88.

Let IR be the set of real numbers and f : IR ➔ IR be such that for all x, y ∈ IR, . Prove that f is a constant function.


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89.

Find the general solution of (x + log(y))dy + ydx = 0


90.

Prove that


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