\(=\left[\left(x+2\right)+\left(x-2\right)\right]\left[\left(x+2\right)-\left(x-2\right)\right]\)
\(=2x4=8x\)
\(\left(x+2\right)^2-\left(x-2\right)^2\)
\(=x^2+4x+4-x^2+4x-4\)
\(=8x\)
\(\left(x+2\right)^2-\left(x-2\right)^2\)
\(=\left(x+2+x-2\right)\left(x+2-x+2\right)\)
\(=2x.4=8x\)
tôi thấy cái này trên olm r thì pải