Question

(x+1)(x²-x+1)-2x=x(x-2)(x+2)

Answer 1

Giải:

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

\(\Leftrightarrow x^3+1-2x=x\left(x^2-4\right)\)

\(\Leftrightarrow x^3+1-2x=x^3-4x\)

\(\Leftrightarrow x^3+1-2x-x^3+4x=0\)

\(\Leftrightarrow1+2x=0\)

\(\Leftrightarrow x=-\dfrac{1}{2}\)

Vậy ...

Answer 2

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

\(\Leftrightarrow x^3-1-2x=x\left(x^2-4\right)\)

\(\Leftrightarrow x^3-1-2x=x^3-4x\)

\(\Leftrightarrow2x=1\Leftrightarrow x=\dfrac{1}{2}\)