\(\left(x^2+x\right)^2+3\left(x^2+x\right)+1\)
\(=\left(x^2+x\right)^2+2.\left(x^2+x\right).1,5+\left(1,5\right)^2-1,25\)
\(=\left(x^2+x+1,5\right)^2-\sqrt{1,25}^2\)
\(=\left(x^2+x+1,5-\sqrt{1,25}\right)\left(x^2+x+1,5+\sqrt{1,25}\right)\)
Chúc bạn học tốt!!!