Bài 4:
b: \(=x^2\left(x-3\right)-\left(x-3\right)=\left(x-3\right)\left(x-1\right)\left(x+1\right)\)
f: \(=2x^2+9x-2x-9=\left(2x+9\right)\left(x-1\right)\)
e: \(=\left(x+y\right)\left(x^2-xy+y^2\right)-xy\left(x+y\right)=\left(x+y\right)\left(x-y\right)^2\)
g: =(x-2)(x-8)
e: =(x+3)(x+4)
i: \(=x^3+3x^2+6x+4\)
\(=x^3+x^2+2x^2+2x+4x+4=\left(x+1\right)\left(x^2+2x+4\right)\)