\(1,x^3+2x^2y+xy^2-4x\)
\(x\left(x^2+2xy+y^2-4\right)\)
\(x\left[\left(x+y\right)^2-2^2\right]\)
\(x\left(x+y+2\right)\left(x+y-2\right)\)
\(2,5x-5y-x^2+2xy-y^2\)
\(5\left(x-y\right)-\left(x^2-2xy+y^2\right)\)
\(5\left(x-y\right)-\left(x-y\right)^2\)
\(\left(x-y\right)\left(5-x+y\right)\)
\(3,x^4-3x^2\)
\(x^2\left(x^2-3\right)\)