Bài 1:
a: \(\Leftrightarrow2x^2+5x-2x-5=0\)
=>(2x+5)(x-1)=0
=>x=-5/2 hoặc x=1
c: \(\Leftrightarrow\left\{{}\begin{matrix}8x+4y=4\\3x+4y=-1\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}5x=5\\2x+y=1\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=1\\y=-1\end{matrix}\right.\)