(x +2)(x-3)=20
x²-x-6=20
x²-x+1/4=26+1/4
(x-1/2)²=105/4
x-1/2=±√105 /2
x1=(√105+1)/2
x2=(-√105+1)/2
x²+4x+2=0
x²+4x+4=2
(x+2)²=2
x+2=±√2
x1=√2-2
x2=-√2-2