Question

giải pt

1/ \(x^4+2008\cdot x^2+2007\cdot x+2008=0\)

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

Answer 1

1: \(\Leftrightarrow x^4+x^3+x^2-x^3-x^2-x+2008x^2+2008x+2008=0\)

\(\Leftrightarrow\left(x^2+x+1\right)\left(x^2-x+2008\right)=0\)

hay \(x\in\varnothing\)

2: \(x^4+x^2+6x-8=0\)

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

\(\Leftrightarrow\left(x-1\right)\left(x^3+x^2+2x+8\right)=0\)

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

hay \(x\in\left\{1;-2\right\}\)