求解(1){2x-y=9 3x+y=7 (2)｛4x-3y=5.6 5x+3y=7.4 (3)｛2x+3y+19=0 x+5y-1=0
问题描述：
求解(1){2x-y=9 3x+y=7 (2)｛4x-3y=5.6 5x+3y=7.4 (3)｛2x+3y+19=0 x+5y-1=0
(4)｛x+y/2+x-y=1 4（x+y)-5(x-y)=2
答
(1)2x-y+(3x+y)=9+7 5x=16 x=16/5把x=16/5代入2x-y=9中32/5-y=9 y=13/5(2)4x-3y+(5x+3y)=5.6+7.4 9x=15 X=15/9把x=15/9代入4x-3y=5.6中y=96/270(3)(X+5Y-1=0)*2 即2X+10Y=22x+3y+19-(2x+10y-2)=-21 y=3把y=3代入2x+3...