`a)(x²-1)(2y+4)=0`
`⇔`$\left\{\begin{matrix} x^2-1=0\\2y+4=0 \end{matrix}\right.$
`⇔`$\left\{\begin{matrix} x^2=1\\2y=-4 \end{matrix}\right.$
`⇔`$\left\{\begin{matrix} x=±1\\y=-2 \end{matrix}\right.$
Vậy `x=1` và `y=-2` hoặc `x=-1` và `y=-2`
`b)|2x-1|-3=0`
`⇔|2x-1|=0+3`
`⇔|2x-1|=3`
`⇔`\(\left[ \begin{array}{l}2x-1=3\\2x-1=-3\end{array} \right.\)
`⇔`\(\left[ \begin{array}{l}2x=3+1\\2x=-3+1\end{array} \right.\)
`⇔`\(\left[ \begin{array}{l}2x=4\\2x=-2\end{array} \right.\)
`⇔`\(\left[ \begin{array}{l}x=2\\x=-1\end{array} \right.\)
Vậy `x=2` hoặc `x=-1`
