Question

9x+8x(5-2x)=9x^2-(5x+7)-(5x-7)

Answer 1

9x+40x-16x=9x^2-5x^2-49
9x+40x-16x- 9x^2+5x^2+49=0
33x+4x^2+49=0
4x^2+33x+49=0
вроде так

Answer 2

$9x+8x(5-2x)=9x^2-(5x+7)-(5x-7),$
$9x+40x-16x^2=9x^2-10x,$
$19x-7x^2=0, \\ 7x^2-19x=0,$
$x(7x-19)=0,$
$\left[\begin{array}{ccc}x=0,\\7x-19=0;\end]$
$\left[\begin{array}{ccc}x=0,\\x= \frac{19}{7} ;\end]$
$\left[\begin{array}{ccc}x=0,\\x=2 \frac{5}{7} .\end]$
Ответ: $0; 2 \frac{5}{7}$.