{2x-1/5+3y-2/4=2 2x+1/5-3y+2/4=0 用加减法解方程组

化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7 3(x+y)+2(x-y)=36 4(x+y)-5(x-y)=2 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 4(x-y)-3(x-y)=9 5(x-y)+2(x-y)=11 3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27 (x-y)/(x+y)=3求( 3x-2y-1)/(x+y-5) 先化简再求值(x-y)(x-2y)+(x-2y)(x-3y)-2(x-3y)(x-4y) x=4 y=5 {x+y=1 ,xy=-6{x(2x-3)=0,y=x²-1{(3x+4y-3)(3x+4y+3)=0,3x+2y=5{(x-y+2)(x+y)=0,x²+y²=8{(x+y)((x+y-1)=0,(x-y)(x-y-1)=0 x+y+2(-x-y+1)=3(1-y-x)-4-(y+x-1),x+y=? {(x+y)/2+(x-y)/3=1,(x+y)-5(x-y)=2.求x=?,y=? (x-y) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)= 化简求值{(x=2y)(5x-2y)-(3x+2y)(3x-2y)]/4x,其中x=2,y=-1 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 3x-2y=1 4x-5y x²/xy-x/y 3x/4x+y - x-2y/4x+y (1-y/y+x)÷x/y²-x² (x-y)/4+(x+y)/5=1/4 (x+y)/9-(x-y)/3=//2(x-y)/4+(x+y)/5=1/4(x+y)/9-(x-y)/3=//2 因式分解(x-2y)(x-3y)+(x-4y)(x-5y)+（x-3y)(x-5y)+(x-2y)(x-4y)