\(16-x^2\)
\(=\left(4-x\right)\left(4+x\right)\)
\(---\)
\(16-3x+1^2\) (kt lại đề bài nhé)
\(x^4y^4+4x^2y^2+4\)
\(=\left[\left(xy\right)^2\right]^2+2\cdot\left(xy\right)^2\cdot2+2^2\)
\(=\left[\left(xy\right)^2+2\right]^2=\left(x^2y^2+2\right)^2\)
\(---\)
\(y^2-4y+4-x^2\)
\(=y^2-2\cdot y\cdot2+2^2-x^2\)
\(=\left(y-2\right)^2-x^2\)
\(=\left(y-2-x\right)\left(y-2+x\right)\)