Bình phương 2 vế , ta được :
\(\left(x^2+x-1\right)^2=\left(x^2+4x+4\right)\left(x^2-2x+2\right)\)
\(\Leftrightarrow x^4+x^2+1+2x^3-2x^2-2x=x^4+4x^3+4x^2-2x^3-8x^2-8x+2x^2+8x+8\)
\(\Leftrightarrow x^4+2x^3-x^2-2x+1=x^4+2x^3-2x^2+8\)
\(\Leftrightarrow x^2-2x-7=0\)
\(\Leftrightarrow\left(x-1\right)^2=8\)
\(\Leftrightarrow x=\pm\sqrt{8}+1\)
Vậy ...