x-5y=0 3x+7y=44

{2x+y/3-2y=0 2(2x+y)-5=7y 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7 y-3x=2,y-5x=4,y-7x=6,y-9x=8,y-11x=0方程组, 若3x-5y=0,则x+y/x=（）,x-y/y=（）,2x-3y/2x+3y=( ) 已知x.x+y.y-6x-8y+25=0,求3x.x+5y的值 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(x+y)(x-2y)=-5 (x-y)(x+2y)=7 （5x+3y)(3y-5x)-(4x-y)(4y+x)= 6(x-y)-2(x+y)=14 3(x-y)+(x+y)=5 3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27 若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于