Question

Tìm x biết : \(\sqrt{x+2}\) \(=\frac{5}{7}\)

Answer 1

\(\sqrt{x+2}=\dfrac{5}{7}\)

\(\Leftrightarrow x+2=\dfrac{25}{49}\Rightarrow x=\dfrac{25}{49}-2=-\dfrac{73}{49}\)

Vậy........

Answer 2

@Ái Hân Ngô

\(\sqrt{x+2}=\dfrac{5}{7}\)

\(\Leftrightarrow\sqrt{x+2}^2=\dfrac{25}{49}\)

\(\Leftrightarrow\left|x+2\right|=\dfrac{25}{49}\)

\(\Leftrightarrow\left[{}\begin{matrix}x+2=\dfrac{25}{49}\\x+2=-\dfrac{25}{49}\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=-\dfrac{73}{49}\\x=-\dfrac{123}{49}\end{matrix}\right.\)