2/5x+1/4y=59 1/4x+2/5y=49 这两个方程如何解2/5x+1/4y=591/4x+2/5y=49这两个方程如何解

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)-4(x-y)=4 {x+y/2 + x-y/6=1 {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 求y=(5x-1)/(4x+2) (x x+y+2(-x-y+1)=3(1-y-x)-4-(y+x-1),x+y=? 3x-2y=1 4x-5y 化简求值{(x=2y)(5x-2y)-(3x+2y)(3x-2y)]/4x,其中x=2,y=-1 (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 （x-4y=-1 2x+y=16) (x-y=1 2x+y=5 ) 初二上学期方程题 4x+y=5 5x+4y=63x-2y=1 2x+3y=13x-2y=7 7x+5y=32x+3y=17 2x-y=-4x+5y=6 2x+y=23x-6y=4 3x+2y=52x+y=73x-4y=53x+y=1x-2y=-1x+y=42x+3y=92x-3y=74x+5y=3x+y=20004x+6y=90003x+5y=113x-2y=42x+3y=215x-2y=5x+y=54x+3y=182x+3y=16x+4y=132x+3y=40x x²/xy-x/y 3x/4x+y - x-2y/4x+y (1-y/y+x)÷x/y²-x² 解下列方程组：{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 4(x+2)=1-5y 4(x+y)-3(x-y)=12 x^2-x+y^2+2y+5/4=0 求x^-1+y^0 （x+2y)(x-2y)(x^2-4y^2),其中x=2,y=-1（x+5)^2-(x-5)^2-5(2x+1)(2x-1)+x·(2x)^2,其中x=-1 4x-3y=5 x^2+y^2=1 求x,y {(x+y)/2=(3x+4y)/5,(x+y)/2=1,