1: =z(x-y)-5(x-y)=(x-y)(z-5)
2: \(=x^2\left(1-x\right)-xy\left(1-x\right)\)
\(=x\left(1-x\right)\left(x-y\right)\)
3: \(=4x^2-\left(t^2+4ty+4y^2\right)\)
\(=\left(2x\right)^2-\left(t+2y\right)^2\)
\(=\left(2x-t-2y\right)\left(2x+t+2y\right)\)
4: \(=-\left(x^2-4x+4-y^2\right)\)
\(=-\left(x-2-y\right)\left(x-2+y\right)\)