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Question

Question: If a root of the equation \(\tan^{- 1}\alpha + \tan^{- 1}\beta\) is 4, while the roots of the equati...

If a root of the equation tan1α+tan1β\tan^{- 1}\alpha + \tan^{- 1}\beta is 4, while the roots of the equation π/4\pi/4 are same, then the value of π/2\pi/2will be.

A

4

B

4/49

C

49/4

D

None of these

Answer

49/4

Explanation

Solution

Put x44x3+6x24x+1=0x^{4} - 4x^{3} + 6x^{2} - 4x + 1 = 0in 8x314x2+7x1=08x^{3} - 14x^{2} + 7x - 1 = 0, we get 1,12,141,\frac{1}{2},\frac{1}{4}

Now second equation 4x3+16x29x36=04x^{3} + 16x^{2} - 9x - 36 = 0 have equal roots. Therefore 2,23,23- 2,\frac{2}{3}, - \frac{2}{3}.