P-x-1-P-x-1-4x-2-8x-a-5-a-

Question Number 11024 by ABD last updated on 07/Mar/17

P (x + 1) \times P (x - 1) = 4 x^{2} + 8 x + a - 5

a = ?

Answered by ajfour last updated on 07/Mar/17

l e t P (x) = b x + c

T h e n P (x + 1) \times P (x - 1)

= (b x + b + c) (b x - b + c)

= {(b x + c)}^{2} - b^{2} = 4 {(x + 1)}^{2} + a - 9

s o, b = c = \pm 2 . a n d a - 9 = - b^{2}

t h u s a - 9 = - 4

a = 5 .

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