x+y=20 1 x-y=16 2
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
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
(3x-y)^2+(3x+y)(3x-y),x=1,y=-2
{3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1
已知4x=9y求(1)x+y/y (2)y-x/2x
1/(x+y)-1/(x+y)=3/20 2/(x+y)+3/(x-y)=19/20 这是
3分之2(X-Y)-4分之X+Y=-1,6(X+Y)-4(2X-Y)=16
解方程组:2(x-y)/3-x+y/4=-1 ,6(x+y)-4(2x-y)=16
集合N={(x,y)|(x-1)^2}+(y-1)^20},M={(x,y)|x^2+y^2
已知集合A={(x,y)| (y-3)/ (x-1)=2,x,y∈R},B={(x,y)| 4x+ay=16,x,y∈