Question

Giải pt

\(x^3+2x^2+2\sqrt{2}x+2\sqrt{2}\)

Answer 1

Phương trình kiểu gì mà chỉ cho mỗi vế trái z??

Answer 2

\(\Leftrightarrow x^3+\left(\sqrt{2}\right)^3+2x\left(x+\sqrt{2}\right)=0\)

\(\Leftrightarrow\left(x+\sqrt{2}\right)\left(x^2-\sqrt{2}x+2\right)+2x\left(x+\sqrt{2}\right)=0\)

\(\Leftrightarrow\left(x+\sqrt{2}\right)\left(x^2+\left(2-\sqrt{2}\right)x+2\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}x+\sqrt{2}=0\\x^2+\left(2-\sqrt{2}\right)x+2=0\left(vn\right)\end{matrix}\right.\)

\(\Rightarrow x=-\sqrt{2}\)