求方程x y=ln(xy)确定的隐函数y=y(x)
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sin(xy)+ln(y-x)=x两边同时对x求导得:cos(xy)·(y+xy')+(y'-1)/(y-x)=1①当x=0时,sin0-lny=0,解得y=1把x=0,y=1代入①得:cos0·(1
方程两边求关x的导数ddx(xy)=(y+xdydx); ddxex+y=ex+y(1+dydx);所以有 (y+xdy
这种题可以直接全微分,即e^xdx+xdy+ydx=0所以dy/dx=(e^x+y)/-x
直接在等式中零,x=0,y=y(0),可得关于y(0)的方程解出y(0)即可.具体:e^0*y(0)+lny(0)/1=0即-y(0)=lny(0)作图y1=-x,y2=ln(x),两者的交点的横坐标
答:xy+ln(x+e^2)+lny=0……(1)两边对x求导:y+xy'+1/(x+e^2)+y'/y=0……(2)x=0代入(1)和(2)得:0+2+lny=0y+0+1/e^2+y'/y=0解得
两边同时对X求导y+xy`=e^x+y`y`=(e^x-y)/(x-1)
两边对x求导得y+xy'=(1+y')/(x+y)y(x+y)+x(x+y)y'=1+y'y'[x(x+y)-1]=1-y(x+y)y'=[1-y(x+y)]/[x(x+y)-1]dy=[1-y(x+
方程两边对变量x求导有d[sin(xy)]/dx=dx/dxcos(xy)*d(xy)/dx=1cos(xy)*(dx*y+x*dy)/dx=1cos(xy)*[y+x*(dy/dx)]=1所以:dy
设Y=y'降阶:Y'=(Y/x)ln(Y/x)这就是一个一阶齐次方程.设Y/x=u,所以Y=ux,Y'=u+x(du/dx),代回原方程,解得:lnu=C1x+1Y=xe^(C1x+1)所以y=[(C
y'=(y+xy')/(xy)xyy'-xy'=yy'=y/(xy-x)所以dy/dx=y'=y/(xy-x)
这不是微分方程.你漏掉导数符号了或者漏掉微分符号d了.再问:没有,篇子上原题,一模一样。再答:你有没有看清楚,其中是不是有个y有个小小的一撇y'这真的不是微分方程,微分方程要含有导数或者偏导或者等价的
两边求导:e^(xy)*(xy)'-(xy)'=0e^(xy)*(y+xy')-(y+xy')=0ye^(xy)+xe^(xy)*y'=y+xy'x(e^(xy)-1)y'=y(1-e^(xy))y'
先求导等式两边同时对x求导得y+xy'+y'/y=0则y'=-y^2/(xy+1)当x=1,y=1时,y'=-1/2故切线方程为y-1=-1/2(x-1)即x+2y-3=0
[ln(xy)]'=[e^(x+y)]'(xy)'/(xy)=e^(x+y)*(x+y)'(y+xy')/(xy)=e^(x+y)*(1+y')y'=y[e^(x+y)-1]/[x(1-ye^(x+y
y+xy'+y'/y=0//对xy和lny分别求导,注意y是x的函数y'(x+1/y)=-y//移项,合并同类项y'=-y²/(xy+1)
xy+lny=1两边求导y+xy'+y'/y=0y'=-y/(x+1/y)=-y^2/(xy+1)
将x=0代入方程得:lny=1,得y=e方程两边对x求导:y+xy'+e^xlny+y'e^x/y=0代入x=0,y=e得:e+lne+y'/e=0,得y'=-e(e+1)即y'(0)=-e(e+1)
两边求导e^y×y'=xy'+yy'=y/(e^y-x)dy/dx=y/(e^y-x)
min是指f(x)g(x)h(x)三个函数中的最小值
e^(x+y)=xy两边对x求导:e^(x+y)*(1+y')=y+xy'解得:y'=[y-e^(x+y)]/(e^(x+y)-x]=(y-xy)/(xy-x)