3X+4Y=10 (1) 4X+3Y=11 (2) (1)+(2) 7X+7Y=21 X+Y=3 3X+3Y=9 (3)
{3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1
{4/(x+y)+6/(x-y)=3 {9/(x-y)-1/(x+y)=1
3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27
化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1
9y=3x-(x-1),4(x+y)-(2x+4)=8y
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+y)-(x-2y) 的完全平方+x(3x-5y)-(x-y)(x-2y),其中x=1/2 y
化简求值:(7x-2y)(3x-2y-1)-(4x+3y)(9x+6y),其中x=2,y=-1
已知X和Y满足3X+4Y=2,X-Y-1/7
{3(x+y)+3(y+x)=1,3(x+y)+4(y-x)=-1
[(2x+y)^2+(y+2x)(y-2x)-2y(4x-y)]/4y,其中x=1/2,y=1/3
(3x-y)^2+(3x+y)(3x-y),x=1,y=-2