Question

Giải phương trình: \(x^4+x^2+6x-8\)

Answer 1

\(x^4+x^2+6x-8=0\)

\(\Leftrightarrow x^4-x^3+4x^2+x^3-x^2+4x-2x^2+2x-8=0\)

\(\Leftrightarrow x^2\left(x^2-x+4\right)+x\left(x^2-x+4\right)-2\left(x^2-x+4\right)=0\)

\(\Leftrightarrow\left(x^2+x-2\right)\left(x^2-x+4\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x^2+x-2=0\\x^2-x+4=0\left(vô-nghiệm\right)\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=1\\x=-2\end{matrix}\right.\)