已知4x—3y=-5,3x+4y=3,则21x+3y

已知:3x-5y=0,求x/y,x-y/y,x-y/x 已知x/5=y/3,则(x/x+y)+(y/x-y)-(yxy/xxx-yxy) 已知4x—3y=-5,3x+4y=3,则21x+3y 已知2y-x=-3,求[4y(2x-y)-2x(2x-y)]/(2x-y 已知x/3=y/4,则x-y/4x+3y= 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 已知(x+y)²=4 (x-y)²=3则x²+y² 已知4x=5y,那么(3x+y)/(x-2y)= 已知3X=4X,5Y=6Z求X+Y：Y+Z 已知3x-4y=0,则x^2-y^2/x^2+y^2 已知-x+y=3,则2(x-y)2次方-4(x-y)+6 已知x,y>0 2x+y+3=xy 求5x+4y最小值 已知实数x,y满足y=x^2+5x-4,则3x-2y最大值为 已知二元一次方程x+y=7,3x+4y=19,则x-y=()x+y=() 已知实数x,y满足（x+y)(x+y+3)-4=0则x+y的值是 已知（x+1)/2=(y+3)/4=(x+y)/5,则（3x+2y+1)/(x+2y+3)的值为——? 已知4x—3y=0,x≠0,则y/x等于多少 已知x-y=1,求[(x+2y)²+(2x+y)(x-4y)-3(x+y)(x-y)]÷y的值