若y除以x等于3,则x y除以x-y等于-搜答案-智慧作业帮

解题思路：本题目关键1/x+1/y=1/3变型，得到x-y和xy的关系式。解题过程：

1/x-1/y=10(y-x)/xy=10y-x=10xy所以原式=[3(y-x)-6xy]/[(y-x)-2xy]=(30xy-6xy)/(10xy-2xy)=24xy/8xy=3

1/x+1/y=3(3x+xy+3y)/(x—xy+y)上下同除以xy=(3/y+1+3/x)/(1/y-1+1/x)=(9+1)/(3-1)=5

3X+XY-3Y/(X-XY-Y)?由1/X-1/Y=3得y-x=3xyx-y=-3xy则3X+XY-3Y/X-XY-Y化简为3(x-y)+xy/(x-y-xy)=3(-3xy)+xy/(-3xy-x

x2+xy-2y2=0(x-y)(x+2y)=0x-y=0,x+2y=0x=y或x=-2yx=y,则原式=(y2+3y2+y2)/(y2+y2)=5y2/2y2=5/2x=-2y,则原式=(4y2-6

X分之一减y分之一=(y-x)/xy=3y-x=3xy2X一14Xy一2y除以x一2xy一y=[2(x-y)-14xy]/[(x-y)-2xy]=[-6xy-14xy]/[-3xy-2xy]=4

y－x－2xy＝0(3x＋xy－3y)/(y－xy－x)＝(3x＋6xy－5xy－3y)/(y＋xy－2xy－x)＝[-3(y－x－2xy)－5xy]/(y－x－2xy)＋xy＝(0－5xy)/(0＋

（x平方+2xy-3y平方）除以（x-y)=(x-y)(x+3y)/(x-y)=x+3y=12

若X>1,y>0,且满足xy=x^y,x/y=x^(3y)相乘得x2=x^(4y)y=0.50.5x=根号x0.25x2=xx=4x+y=4.5

X大于1,y大于0xy等于x的y次方,所以lgx+lgy=y乘以lgxx除以y等于x的3y次方,所以lgx-lgy=3y乘以lgx相加得2lgx=4y乘以lgxy=0.5xy等于x的y次方,即0.5X

1/x-1/y=3通分(y-x)/xy=3y-x=3xyx-y=-3xy原式=[(x-y)-xy]÷[5(x-t)+xy]=(-3xy-xy)/(-15xy+xy)=-4xy/(-14xy)=2/7

等会再答：x=24/7y=24/5z=24再问：请告诉我过程。再答：过程就是，按题目列等式，然后等式两边同取倒数，左边把它分解成分式。列出三个方程，组成三元一次方程组解得。再问：不明白，麻烦你写一下。

由题意得：xy=3（x+y）原式=[2x+2y-9(x+y)]%[-x-y+9(x+y)]=[-7(x+y)]%[8(x+y)]=-7/8(因为x+y不等于0)

4.5÷x=4÷y4.5y=4xy=8/9*x所以x和y成正比例

8x=7/y可转化为x=7/8y所以,随着y的增大,x逐渐减小,所以x、y成反比例关系再问：好那我做对了，这次考试满分，有一定的可能性了。再答：哦，原来是个数学尖子呀，幸亏我学习不错，要不就要被你鄙视

(2x-14xy-2y)除以(x-2xy-y)=4(2x-14xy-2y)=4(x-2xy-y)2x+6xy-2y=0x-y=-3xy两边同除以xy,得1/y-1/x=-3所以1/x-1/y=3

因式分解原式=[x(x-2)]/[-y(x-2)]=-x/y

x^2+9y^2-8xy=0(x-9y)(x+y)=0x=9yx=-y1)x=9y(x+3y)(x-3y)=12/6=22)x=-y(x+3y)(x-3y)=2/(-4)=-1/2再问：做错了……再答

3x除以4等于2y除以5两边乘以4/3左边=x右边=y*2/5*4/3=y*8/15所以x除以y等于8除以15