Решите уравнение: x(x²+x-12)=5(x-3).

X(x2+x–12)=5(x–3). 
x1=(–1–7)/2=–4
x2=(–1+7)/2=3
x2+x–12=(x+4)(x–3)
x(x+4)(x–3)–5(x–3)=0
(x–3)(x2+4x–5)=0. 
x–3=0 или x2+4x–5=0
x1=3 D=16+20=36
x2=(–4–6)/2=–5
x3=(–4+6)/2=1