Question

giúp mình với

Answer 1

a) \(\left(2x+1\right)\left(2x-3\right)=0\)

\(\left[{}\begin{matrix}2x+1=0\\2x-3=0\end{matrix}\right.\)

\(\left[{}\begin{matrix}2x=-1\\2x=3\end{matrix}\right.\)

`=>`\(\left[{}\begin{matrix}x=-\dfrac{1}{2}\\x=\dfrac{3}{2}\end{matrix}\right.\)

Vậy \(x\in\left\{-\dfrac{1}{2};\dfrac{3}{2}\right\}\)

b) \(x^2-9=0\)

\(x^2=0+9\)

`x^2=9`

`x^2=3^2`

`=>`\(\left[{}\begin{matrix}x=3\\x=-3\end{matrix}\right.\)