Question

(x + 4)2 – (x – 5)2 = 9​

Answer 1

Answer:

2x+8-5x-10=9

2x-5x+8-10=9

3x+2=9

3x=9-2

3x=7

X=7\3

Answer 2

(x+4)^2 - (x-5)^2 = 9

Using identity (a+b)^2 = a^2 + b^2 +2ab

             and  (a-b)^2 = a^2 + b^2 - 2ab

x^2 + 16 + 8x - [ x^2 + 25 - 10x] = 9

x^2 + 16 +8x -x^2 -25 + 10x = 9

2x^2 +18x -9 = 9

2x^2 +18x -18 = 0

Dividing equation by 2

x^2 + 9x - 9 = 0

By quadratic formula

x =( -9+_ root13)/2