Question

Cho hàm số \(y=f\left(x\right)=x^2-1\) . Tìm x sao cho \(f\left(x\right)=1\)

Answer 1

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

Answer 2

Giải:

Vì \(f\left(x\right)=1.\)

\(\Rightarrow x^2-1=1.\)

\(\Rightarrow x^2=2.\)

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

Vậy \(x=\left\{\sqrt{2};-\sqrt{2}\right\}.\)