\(A=\left(x^2+x\right)+3\left(x^2+x\right)+2\)
\(A=4\left(x^2+x\right)+2\)
\(A=2\left(2x^2+2x+1\right)\)
Sửa đề: \(\left(x^2+x\right)^2+3\left(x^2+x\right)+2\)
\(=\left(x^2+x\right)^2+2\left(x^2+x\right)+\left(x^2+x\right)+2\)
\(=\left(x^2+x+2\right)\left(x^2+x+1\right)\)