Question

giải hệ pt và pt sau:

a) 3x-2y=3 và 2x+2y=2

b) x^2+7x-12=0

Answer 1

a)\(\left\{{}\begin{matrix}3x-2y=3\\2x+2y=2\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}5x=5\\3x-2y=3\end{matrix}\right.\)

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

b)\(x^2+7x+12=0\)

\(\Leftrightarrow x^2+3x+4x+12=0\)( chị nghĩ + 12 đúng hơn á )

\(\Leftrightarrow x\left(x+3\right)+4\left(x+3\right)=0\)

\(\Leftrightarrow\left(x+3\right)\left(x+4\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}x+3=0\\x+4=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=-3\\x=-4\end{matrix}\right.\)