Question

(x+1)(x+2)=56
x=? mate cls a 5-a

Answer 1

$x^{2} +2x+x+2=56$
$x^{2} +3x+2-56=0$
$x^{2} +3x-54=0$
$delta=b^2-4ac$
$delta=3^2-4*1*(-54)=9+216=225 <=> \sqrt{225}=15$
$x_{1} =(-b+15)/2a=-3+15/2=12/2=6$]
$x_{2} =(-b-15)/2a=-3-15/2=-18/2=-9$
x∈{6,-9}