{x/3-y=5 (1) {x/4-y=1 (2) {5x+2y=5 (1) {2x+5y=8 (2)
分式的加减:[(x/y-y/x)除以(x+y)+x(1/y-1/x)]除以1+x/y,其中x=5,y=2
10/x+y+3/x-y=-5 15/x+y-2/x-y=-1(用换元法解此方程组)
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
解方程组:(0.2x+0.1y)/2- (4x-y)/10=(x-y)/5+ (3x+0.5y)/30 (3x+2y-1
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)+...-(
先化简再求值(x-y)(x-2y)-1/2(2x-3y)(x+2y),其中x=2,y=2/5
(5x-y)(y+5x)-(3y+2x)(3y-2x) x=1 y=2
化简求值(x+5y)(x+4y)-(x-y)(x+y),其中x=一又2/5,y=-1/7
先化简,再求值:[(X+2Y)平方-(X+Y)(3X-Y)-5Y平方]除以(2X)其中X=-2,Y=1/2
(1)已知x+y=6,x²-y²=5,求x-y的值(2)若x+y=3,x²+y²
1、已知x=2y,则x-5y/x+y=()