Question

\(\left\{{}\begin{matrix}\text{- 6x + 4y = - 2}\\3x+4y=9\end{matrix}\right.\)

Giải hpt bằng phương pháp thế

Answer 1

\(\left\{{}\begin{matrix}-6x+4y=-2\\3x+4y=9\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}3x-2y=1\\3x+4y=9\end{matrix}\right.\)

=>\(\left\{{}\begin{matrix}3x=2y+1\\2y+1+4y=9\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}3x=2y+1\\6y=8\end{matrix}\right.\)

=>\(\left\{{}\begin{matrix}y=\dfrac{8}{6}=\dfrac{4}{3}\\x=\dfrac{2y+1}{3}=\dfrac{2\cdot\dfrac{4}{3}+1}{3}=\dfrac{\dfrac{8}{3}+1}{3}=\dfrac{11}{3}:3=\dfrac{11}{9}\end{matrix}\right.\)