(5/2)x+(2/3)y=-10

来源：学生作业帮编辑：大师作文网作业帮分类：数学作业时间：2024/11/19 22:58:37

(5/2)x+(2/3)y=-10
x/3-y/9=1
(x-y)/5-(x+y)/2=-1/10
(x-y)/7-(x+y)/6=1/2

(5/2)x+(2/3)y=-10 --(1)
x/3-y/9=1 --(2)
由（2）得x=3+1/3y 代人（1）
有2/5(3+1/3y)+2/3y=-10
y=-35/3
代入x=3+1/3y x=-8/9
所以x=-8/9
y=-35/3
第二题上面有答案,思路可以把x+y、x-y看分别看做一个整体

(4x-2y-z)-{5x[8y-2y-(x+y)]-x+(3y-10z)]=? kuai 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 已知x,y满足约束条件{2x+5y>=10,2x-3y>=-6,2x+y { x-y/7-x+y/10=1/2 {2(x-y)+5(x+y)=3 10/x+y+3/x-y=-5 15/x+y-2/x-y=-1（用换元法解此方程组） 6(x-y)-2(x+y)=14 3(x-y)+(x+y)=5 3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27 3x+2y=6 ,5x+6y=10那么x+y=? [-(x-y)^2/xy]^-4*(y^2-xy/x)^3*(x^4/y^10)÷(xy-y^2/x)^-5=-y(y- 已知X,Y,满足(X+3Y)(X-3Y)=-10(Y^2-6/5)和2X(Y-1)+4(1/2X-1)=0 解方程组：（0.2x+0.1y）/2- （4x-y）/10=（x-y）/5+ (3x+0.5y)/30 (3x+2y-1