Hoặc
4x+y=172x+3y=1⇔y=17−4x2x+3y=1⇔y=17−4x2x+3(17−4x)=1⇔y=17−4x2x+51−12x=1⇔y=17−4x10x=50⇔y=17−4xx=5 ⇔x=5y=−3