2/5x+2/3y=-10 ① x/3-y/9=1 ② 解方程组 x-y/5-x+y/2=-1/10① x-y/7-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：2024/10/06 22:23:24

2/5x+2/3y=-10 ① x/3-y/9=1 ② 解方程组 x-y/5-x+y/2=-1/10① x-y/7-x+y/6=1/2②

2/5x+2/3y=-10 (1) x/3-y/9=1 (2)
(1)*15 得 6x+10y=-150 (3)
(2)*9 得 3x-y=9 (4）
（3)-(4)*2 得 y=-14 代入（4）得x=-5/3
再问：第二个方程呢？
再答： x-y/5-x+y/2=-1/10 (1) x-y/7-x+y/6=1/2 (2) (1)*10 得3x+7y=1(3) (2)*42 得 x+13y=-21(4) (4)*3-(3) 得y=-2 代入（4）得x=5

10/x+y+3/x-y=-5 15/x+y-2/x-y=-1（用换元法解此方程组）解方程组：（0.2x+0.1y）/2- （4x-y）/10=（x-y）/5+ (3x+0.5y)/30 (3x+2y-1 解方程组(x+y)(x-2y)=-5 (x-y)(x+2y)=7 解方程组:(x+3)(y-2)=(x-3)(y+10),(x+1)(y+3)=(x-2)(y+12) 解方程组{(x-2)(y+3)=(x+1)(y-1) {(x+1)(y+1)=(x-1)(y+5) 解方程组: ｛3x+2y=13 3x-2y=5 ｛x-y/3=x+y/2+1 2x-5y=9 解方程组 2x+y(y-2x)=9 (x+y)(x+y-3)=10 解方程组:2/(x+y)+5/(x-y)=18 9/(x+y)-10/(y-x)=66 解方程组：2/(x+y)+5/(x-y)=18 9/(x+y)-10/(y-x)=66 解二元一次方程组:{5(x+y)+3(x-y)=2{7(x+y)-3(x-y)=-6 换元法解方程组3/x+y+2/x-y=17/5 2/x+y-5/x-y=1 2(x+y)-3(x-y)=1 6(x+y)+7(x-y)=51 解方程组