X+Y/X=2,X/Y=?是（x+y）/x=2哦

x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 X+Y/X=2,X/Y=?是（x+y）/x=2哦 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（） 化简 x / y(x+y) - y / x(x+y) = 对于(y一撇）y`=y/x(y-1)求导,我求的结果是y``=-y^2-y`x+y/x^2(y-1)^2 怎么不对啊,我的求导过程是：y`x(y-1) - [x(y-1)]` y y`xy-y`x-(y-1+xy`)y -y^2-y`x+yy``=-------------------------=----------------------=-----------------x^2 (y-1 x(x+y)(x-y)-y(y+x)(y-x)=(x-y)( )填空 （x+y）/2- x-y/2=6 3(x+y)=4(x-y) x（x-2y）=y(2y-x) ,则y分之x是多少 若x-y不等于0,2x-3y=0,则分式(10x-11y)/(x-y)的值是（）?(10x-11y)/(x-y) =[(8x-8y)+(2x-3y)]/(x-y) =8为什么8X-8Y=8？(10x-11y)/(x-y)=[(8x-8y)+(2x-3y)]/(x-y)=8+(2x-3y)]/(x-y)=8+0=8 高数中偏导数的问题求函数Z=(X*X*Y*Y)/(X-Y）对自变量X的偏导数怎么做啊?书上是这么写的.将Y看成常数,对X求导,得【2X*Y*Y（X-Y）-X*X*Y*Y】/(X-Y)(X-Y)在化简一下就是【X*X*Y*Y-2X*Y*Y*Y】/(X-Y)(X-Y)我想问 把6x（x－y）的平方＋3（y－x）的立方分解因式我知道答案是6x(x-y)^2+3(y-x)^3=6x(x-y)^2-3(x-y)^3=3(x-y)^2[2x-(x-y)]=3(x-y)^2(x+y)可为什么=6x(x-y)^2-3(x-y)^3=3(x-y)^2[2x-(x-y)] y'=（y/x）^2+y/x+4微分方程 填空：x-y/x+y=( )/x^2-y^2 （x-y)2•(y-x)³(x-y)=? y=x(x 求证f（x+y）+f(x-y)=2f(x)f(y)是周期函数 3x+y=2 -y/x+y=123x+y=2 （-y/x）+y=12 求y''+2y'+y=e^-x/x的通解y''+2y'+y=（e^-x）/x