Question

GPT:[x+√(x^2+9)] * [√(x+21)-x]=9

Answer 1

_{giúp mik vs...}

Answer 2

ĐKXĐ: \(x\ge-21\)

\(\left(x+\sqrt{x^2+9}\right)\left(\sqrt{x+21}-x\right)=9\)

\(\Leftrightarrow\left(\sqrt{x^2+9}-x\right)\left(\sqrt{x^2+9}+x\right)\left(\sqrt{x+21}-x\right)=9\left(\sqrt{x^2+9}-x\right)\)

\(\Leftrightarrow\sqrt{x+21}-x=\sqrt{x^2+9}-x\)

\(\Leftrightarrow\sqrt{x+21}=\sqrt{x^2+9}\)

\(\Leftrightarrow x+21=x^2+9\)

\(\Leftrightarrow x^2-x-12=0\)

\(\Leftrightarrow...\)