Question

方程组计算（1）2x+3y=16 ,x+4y=13(2)7x-2y=3 ,9x+2y=-19(3) 3(x+y)-2(x

Answer 1

（1）2x+3y=16 ,x+4y=13

x=5,y=2

(2)7x-2y=3 ,9x+2y=-19

x=-1,y=-5

(3) 3(x+y)-2(x-y)=7 ,2(x+y)-(x-y)=3

x+y=-1,x-y=-5

x=-3,y=2