x-y=4 ……①
4x+2y= -1 ……②
②+2*①得
4x+2x=4*2-1
x=7/6
y=-17 x-y=4 ……①
4x+2y= -1 ……②
②+2*①得
4x+2x=4*2-1
x=7/6
y=-17