4x+5y=1 5x+4y=-14x+5y=1 1 5x+4y=-1 21式*5 得 20x+25y=52式*4 得 20x+16y=-49y=5-(-4)=9

5x-4y(y-x)=? y=|-x.x+4x+5| 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 （5x+3y)(3y-5x)-(4x-y)(4y+x)= x*x+2x+y*y-4y+5=0 x= y= 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 3(x+y)+2(x-y)=36 4(x+y)-5(x-y)=2 1:4(x-100)+3y=5 2:6(x-y)-2(x+y )=14 x-100=-y 3(x-y)+(x+y)=5 先无视上面的1.4(x-100)+3y=5x-100=-y2.6(x-y)-2(x+y )=143(x-y)+(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 若(x*x+y*y)(x*x+y*y)-4x*x*y*y=0,求代数式(x*x+5xy+y*y)/(x*x+2xy+y*y)的值 x+y／y=5／4,则x／y=---------------- 已知：4x = 5y,求(x+y) ：y 已知x*x+4x+y*y-2y+5=0,则x*x+y*y=? {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+5x-4x= ?x-y+5x-4x= ? 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7 5x+14=y,7x+4=y