Giải:
\(x^2-4+\left(x-2\right)^2\)
\(=x^2-2^2+\left(x-2\right)^2\)
\(=\left(x+2\right)\left(x-2\right)+\left(x-2\right)^2\)
\(=\left(x-2\right)\left[\left(x+2\right)+\left(x-2\right)\right]\)
\(=\left(x-2\right)\left(x+2+x-2\right)\)
\(=\left(x-2\right).2x\)
Chúc bạn học tốt!!!
