2^x=3 2^y=5 2^3x-y=等于多少

如果x乘y=-2,x加y=3,x,y分别等几 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 已知x/3=y/5=z/4,求x+y+z/y和x+y-z/y-x的值,2种方法.急等. 若(5x+2y-3)²+|3x+2y-5|=0则2x+y等什么 x+y/2+x-y/6=5 2(x+y)-3(x-y)=-2 x,y∈R+求证:(x+y)(x^2+y^2)(x^3+y^3)>=8x^3y^3在线等啊 答对加分！！ 3(x+y)+2(x-y)=36 4(x+y)-5(x-y)=2 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 6(x-y)-2(x+y)=14 3(x-y)+(x+y)=5 (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) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)= (x+y)(x-y)+(x-y)平方-(x-y)(3x-y) 其中x=-2 y=3分之一 x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 (x+y)(2x-3y)=? {(x+y)/2+(x-y)/3=1,(x+y)-5(x-y)=2.求x=?,y=? 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1