求解(1){2x-y=9 3x+y=7 (2)｛4x-3y=5.6 5x+3y=7.4 (3)｛2x+3y+19=0 x

来源：学生作业帮编辑：神马作文网作业帮分类：数学作业时间：2024/11/17 14:13:02

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

(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=2
2x+3y+19-(2x+10y-2)=-21 y=3
把y=3代入2x+3y+19=0
x=-2/5
(4)化简{2x-y/2=1 -x+9y=2
(-x+9y=2)*2 -2x+18y=4
-2x+18y+(2x-y/2)=5 y=2/7
把y=2/7代入-x+9y=2
x=4/7

已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 先化简再求值(x-y)(x+y)-(x-2y) 的完全平方+x(3x-5y)-(x-y)(x-2y),其中x=1/2 y 求解 3x=6y-2 3x-4y=2 6x-3y=-5 4x-9y+1=0 4(2x+y)-5(2x-y)=3 2(2x {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 已知x=1/3,y=-1/2,求代数式x-(x+y)+(x+2y)-(x+3y)+(x+4y)-(x+5y)+...-( 已知X-Y/X+Y=3,求代数式2(x-y)/X+Y-3X+Y/X+Y 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7 9y=3x-(x-1),4(x+y)-(2x+4)=8y (3x-y)^2+(3x+y)(3x-y),x=1,y=-2 x+y/2+x-y/3=6,4(x+y)-3(x-y)=-20