设函数 是由方程 确定的隐函数,则
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方程两边同时求x对y的导:y+xdy/dx+1/x+2ydy/dx=0,dy/dx=-(y+1/x)/(x+2y),dy=-(y+1/x)dx/(x+2y)
xy+e^y=y+1(1)求d^2y/dx^2在x=0处的值:(1)两边分别对x求导:y+xy'+e^yy'=y'y/y'+x+e^y=1(2)(2)两边对x再求导一次:(y'y'-yy'')/y'^
cos(xy)=x+y两边微分,得dx+dy-sin(xy)*(x*dy+y*dx)=0dx(1-ysin(xy))+dy(1-xsin(xy))=0dy/dx=(ysin(xy)-1)/(1-xsi
令F(x,y)=cos(xy)-x-yF'(x,y)x=-ysin(xy)-1对x求偏导F'(x,y)y=-xsin(xy)-1对y求偏导切线方程为:(x-0)/F'(x,y)=(y-1)/F'(x,
dcos(xy)=dx-sin(xy)d(xy)=dx-sin(xy)(ydx+xdy)=dx-ysin(xy)dx-xsin(xy)dy=dxdy=-[ysin(xy)+1]dx/[xsin(xy)
e^y-xy=ee^y·dy/dx-(y+x·dy/dx)=0e^y·dy/dx-y-x·dy/dx=0(e^y-x)·dy/dx=ydy/dx=y/(e^y-x)dy/dx不能叫做dx分之dy,因为
y=1+xe^y两边对x求导得y'=e^y+xe^y*y'(是对x求导那么e^y就是一个复合函数了所以最后要在对y求导)(1-xe^y)y'=e^y∴y'=e^y/(1-xe^y)再问:还不是很明白这
对y求导,e^z*z'(y)=xz+xyz'(y),əz/əy=z'(y)=xz/(e^z-xy)
两边微分e^zdz-yzdx-xzdy-xydz=0(e^z-xy)dz=yzdx+xzdy∂z/∂y=xz/(e^z-xy)=xz/(xyz-xy)=z/(yz-y)
对方程两边求全微分得:(e^z-1)dz+y^3dx+3xy^2dy=0(方法和求导类似)移项,有dz=-(y^3dx+3xy^2dy)/(e^z-1)
(-2y^2)/(4xy+e^y)
e^z-z+xy^3=0偏z/偏x:z'e^z-z'+y^3=0y^3=z'(1-e^z)z'=y^3/(1-e^z)偏z/偏y:z'e^z-z'+3xy^2=0z'=3xy^2/(1-e^z)偏z/
对X的偏导=yz/(e^z-xy)对Y的偏导=xz/(e^z-xy)
两边对X求导数就行了撒,把y看成是一个常数,Z看成对x函数就行了撒e^x-(z*y+y*x*zx)=0所以z对x的偏导数zx=(zy-e^x)/(y*x)
dz=-dx-dy
1、2x+2y*dy/dx-y-x*dy/dx=02x-y=(x-2y)dy/dx所以dy/dx=(2x-y)/(x-2y)2、2y*dy/dx-2ay-2ax*dy/dx=0(2y-2ax)dy/d
对左右两边求导:(1+ez)dz=ydx+xdy.dz=1/(1+ez).(ydx+xdy).
F(x,y)=x^2+y^2-ln(x+2y)Fx=2x-1/(x+2y)Fy=2y-2/(x+2y)F(x)=-Fx/Fy=-[2x(x+2y)-1]/[2y(x+2y)-2]