Δ = (2(m+1))2-4.2m
= 4m2+4m+1-8m
=4m2-4m+1
=(m-2)2
do Δ≥0 nên pt có 2 ngo x1 ,x2
áp dụng viet \(\left\{{}\begin{matrix}x1+x2=2m+2\\x1.x2=2m\end{matrix}\right.\)
x12.x2+x1.x22=8
x1.x2.(x1+x2)=8
2m(2m+2)=8
4m2+4m-8=0
m2+m-2=0
m2-m+2m-2=0
m(m-1)+2(m-1)=0
(m+2)(m-1)=0
m=1 hoặc m =-2