Question

(x-1)(x^2+x+1)-(x-1)(2-x)-x^3
Rút gọn

Answer 1

\(=x^3-1-\left(2x-x^2-2+x\right)-x^3\)

\(=x^3-1-2x+x^2+2-x-x^3\)

\(=\left(x^3-x^3\right)+\left(-2x-x\right)+\left(-1+2\right)\)

\(-3x+1\)

Answer 2

\(\left(x-1\right)\left(x^2+x+1\right)-\left(x-1\right)\left(2-x\right)-x^3\)

\(=x^3-1-\left(2x-x^2-2+x\right)-x^3\)

\(=x^3-1-2x+x^2+2-x-x^3\)

\(=\left(x^3-x^3\right)+\left(-2x-x\right)+\left(-1+2\right)+x^2\)

\(=-3x+1+x^2\)

\(=x^2-3x+1\)