\(\left(3x-1\right)^2=49\)
\(\Rightarrow\left(3x-1\right)^2=\left(\pm7\right)^2\)
\(\Rightarrow\left[{}\begin{matrix}3x-1=7\\3x-1=-7\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}3x=7+1\\3x=-7+1\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}3x=8\\3x=-6\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=\dfrac{8}{3}\\x=-\dfrac{6}{3}\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=\dfrac{8}{3}\\x=-2\end{matrix}\right.\)
Vậy: ...
Lời giải:
$(3x-1)^2=49=7^2=(-7)^2$
$\Rightarrow 3x-1=7$ hoặc $3x-1=-7$
$\Rightarrow x=\frac{8}{3}$ hoặc $x=-2$
