What is the implicit derivative of 1= x/y-e^(xy) 1=xyexy?

1 Answer
Apr 1, 2018

dy/dx=(y-e^(xy)y^3)/(x-xe^(xy)y^2)dydx=yexyy3xxexyy2

Explanation:

1=x/y-e^(xy)1=xyexy

First we have to know that we can differentiate each part separately

Take y=2x+3y=2x+3 we can differentiate 2x2x and 33 seperately

dy/dx=dy/dx2x+dy/dx3 rArrdy/dx=2+0dydx=dydx2x+dydx3dydx=2+0

So similarly we can differentiate 11, x/yxy and e^(xy)exy separately

dy/dx1=dy/dxx/y-dy/dxe^(xy)dydx1=dydxxydydxexy

Rule 1: dy/dxC rArr 0dydxC0 derivative of a constant is 0

0=dy/dxx/y-dy/dxe^(xy)0=dydxxydydxexy

dy/dxx/ydydxxy we have to differentiate this using the quotient rule

Rule 2: dy/dxu/v rArr ((du)/dxv-(dv)/dxu)/v^2dydxuvdudxvdvdxuv2 or (vu'-uv')/v^2

u=x rArr u'=1

Rule 2: y^n rArr (ny^(n-1)dy/dx)

v=y rArr v'=dy/dx

(vu'+uv')/v^2=(1y-dy/dxx)/y^2

0=(1y-dy/dxx)/y^2-dy/dxe^(xy)

Lastly we have to differentiate e^(xy) using a mixture of the chain and the product rule

Rule 3: e^u rArr u'e^u

So in this case u=xy which is a product

Rule 4: dy/dxxy=y'x+x'y

x rArr 1

y rArr dy/dx

y'x+x'y=dy/dxx+y

u'e^u=(dy/dxx+y)e^(xy)

0=(1y-dy/dxx)/y^2-(dy/dxx+y)e^(xy)

Expand out

0=(1y-dy/dxx)/y^2-dy/dxxe^(xy)+ye^(xy)

Times both sides by y^2

0=y-dy/dxx-dy/dxxe^(xy)y^2+ye^(xy)y^2

0=y-dy/dxx-dy/dxxe^(xy)y^2+e^(xy)y^3

Place all the dy/dx terms on one side

y-e^(xy)y^3=dy/dxx-dy/dxxe^(xy)y^2

Factorize out dy/dx on the RHS (right hand side)

-y-e^(xy)y^3=dy/dx(x-xe^(xy)y^2)

(-(y+e^(xy)y^3))/(x-xe^(xy)y^2)=dy/dx