Question

Giải hệ phương trình: { x-30y=-30 1,5x-20y=30

Answer 1

\(\left\{{}\begin{matrix}x-30y=-30\\1,5x-20y=30\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}x=30y-30\\1,5\left(30y-30\right)-20y=30\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}x=30y-30\\45y-45-20y=30\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}x=30y-30\\25y=75\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}x=30.3-30\\y=3\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}x=60\\y=3\end{matrix}\right.\)