Question

Considere as expressões: A = 5 (x - 3) – 2x (x - 3) e B = 4 – (3x + 1)^2. Resolva a equação A = B – 18.

Answer 1

=>
$A=5(x-3)-2x(x-3)\\A=5x-15-2x^2+6x\\A=-2x^2+11x-15$

=>
$B=4-(3x+1)^2\\B=4-(9x^2+6x+1)\\B=-9x^2-6x+3$

 Segue,

$A=B-18\\\\-2x^2+11x-15=-9x^2-6x+3-18\\\\7x^2+17x=0\\\\x(7x+17)=0\\\\\boxed{x'=0}\\\boxed{x''=\frac{-17}{7}}$