d) 2x + 3y = -11 và 3x - 5y = 31

d) $\left\{\begin{array}{l}2x+3y=-11\\ 3x-5y=31\end{array}\right.$

Trả lời

$$\begin{gathered} d) \left\{\begin{array}{l}2x+3y=-11\\ 3x-5y=31\end{array}\right.\iff \left\{\begin{array}{l}6x+9y=-33\\ 6x-10y=62\end{array}\iff \left\{\begin{array}{l}2x+3y=-11\\ 19y=-95\end{array}\right.\right. \\ \iff \left\{\begin{array}{l}2x+3y=-11\\ y=-5\end{array}\right.\iff \left\{\begin{array}{l}x=2\\ y=-5\end{array}\right. \end{gathered}$$