rút gọn:
a\(\left(x+1\right)^3+x\left(x-2\right)^2-1\)
b) \(\left(x+1\right)\left(x^2+x+1\right)^2\left(x-1\right)\)
c) \(2x\left(2x-1\right)^2-3x\left(x+3\right)\left(x-3\right)-4x\left(x+1\right)^2\)
d) \(\left(a-b+c\right)^2\left(b-c\right)^2+2ab-2ac\)
\(\left(x+1\right)^3+x\left(x-2\right)^2-1=x^3+3x^2+3x+1+x\left(x^2-4x+4\right)-1\)
\(=x^3+3x^2+3x+1+x^3-4x^2+4x-1\)
\(=2x^3-x^2+7x\)