若3^x=12,3^y=4,则9^x-y=谢谢

比例线段若x+y/x-y=4/3,则x/y=x+y/x-y=4/3,则x/y=要快~~ 若x+y=4,则多项式1/2(x+y)+4(x-y)-3（x-y）-3/2(x+y)-x+y值是（） 若x-2y=5,则式子12-x+2y=.以知3x-4y=2x+y则x∶y= 3(x+y)-2(x-y)=11 4(x+y)+3(x-y)=9 4(x-y)-3(x-y)=9 5(x-y)+2(x-y)=11 若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于 若3x=4y,则x:y等于 若2x=3y,则(x*x+y*y)/x*x=? 若4x-3y=0(y不等于0)则x+y/y= 若x:y=3则x:(x+y)= 若2x+3y=2004,则代数式2(3x-2y)-(x-y)+(-x+9y)=... 若5x+3y=3x+4y=x+2y+6,则x+y=___ 若2x+y=2012,则代数式2(3x-2y)-(x-y)+(-x+9y)= (x-y) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)= 若x+y=4 4x+3y=15则 x-y=? 若x/y=4/3 则3x+2y/2x-5y= 4-12(x-y)+9(x-y)² =(2-3x+3y)² 分式 4y-3x+0 ,则(x+y):y=若 4y-3x+0 ,则(x+y):y=若 4y-3x=0 ,则(x+y):y=