(2x+3)2 \(=\) \(\dfrac{9}{121}\)
(2x+3)2 \(\left(\dfrac{3}{11}\right)^2\)
\(\Rightarrow\) \(\left\{{}\begin{matrix}2x+3=\dfrac{3}{11}\\2x+3=\dfrac{-3}{11}\end{matrix}\right.\)
\(\Rightarrow\) \(\left\{{}\begin{matrix}2x=\dfrac{3}{11}-3\\2x=\left(\dfrac{-3}{11}-3\right)\end{matrix}\right.\)
\(\Rightarrow\) \(\left\{{}\begin{matrix}2x=\dfrac{3}{11}-\dfrac{33}{11}\\2x=\left(\dfrac{-3}{11}-\dfrac{33}{11}\right)\end{matrix}\right.\)
\(\Rightarrow\) \(\left\{{}\begin{matrix}2x=\dfrac{-30}{11}\\2x=\dfrac{-36}{11}\end{matrix}\right.\)
\(\Rightarrow\) \(\left\{{}\begin{matrix}x=\dfrac{-30}{11}:2\\x=\dfrac{-36}{11}:2\end{matrix}\right.\)
\(\Rightarrow\) \(\left\{{}\begin{matrix}x=\dfrac{-15}{11}\\x=\dfrac{-18}{11}\end{matrix}\right.\)
Vậy x \(=\) \(\dfrac{-15}{11}\) và \(\dfrac{-18}{11}\)
Ý cậu là vậy hả ?
\(\left(2x+3\right)^2=\dfrac{9}{121}\)
\(\Leftrightarrow\left(2x+3\right)^2=\left(\dfrac{3}{11}\right)^2\)
\(\Leftrightarrow2x+3=\dfrac{3}{11}\)
\(\Leftrightarrow2x=\dfrac{-30}{11}\)
\(\Leftrightarrow x=\dfrac{-15}{11}\)
Vậy \(x=\dfrac{-15}{11}\)
