大师作文网2x+3y=-15,3x-2y=10
把第一个编为a.第二个编为b然后2a加3b得4x加9x等于0所以x等于0把x等于0带入a得y等于负5
已知X-Y/X+Y=3,求代数式2(x-y)/X+Y-3X+Y/X+Y
已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y)
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 10（x-y)=3(x+y)+15 6(x+y)=4(2x-y)+16
【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2=
(4x-2y-z)-{5x[8y-2y-(x+y)]-x+(3y-10z)]=? kuai
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
(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
{(x+y)/2+(x-y)/3=6 4(x+y)-3(x-y)=-20
4(x+y)-3(x-y)=-20,2/x+y+3/x-y=6
6(x-y)-2(x+y)=14 3(x-y)+(x+y)=5