How do you implicitly differentiate -3=(x^2+y)^3-y^2x 3=(x2+y)3y2x?

1 Answer
Apr 28, 2017

color(red){dy/dx = [6x(x^2+y)^2 - y^2]/[2xy - 3(x^2+y)^2]}dydx=6x(x2+y)2y22xy3(x2+y)2

Explanation:

Implicit differentiation is basically done in cases where yy cannot be explicitly written as a function of xx.

In this case,

-3=(x^2+y)^3-y^2x 3=(x2+y)3y2x

Differentiating both sides w.r.t. xx

=> -3(d(1))/dx = [d(x^2+y)^3]/dx - (d(y^2x))/dx3d(1)dx=d(x2+y)3dxd(y2x)dx

**Using chain rule to evaluate [d(x^2+y)^3]/dxd(x2+y)3dx & product rule to evaluate (d(y^2x))/dxd(y2x)dx **

=> 0 = [d(x^2+y)^3]/(d(x^2+y))*[d(x^2+y)]/dx - [y^2dx/dx + xdy^2/dx]0=d(x2+y)3d(x2+y)d(x2+y)dx[y2dxdx+xdy2dx]

=> y^2dx/dx + xdy^2/dx = [d(x^2+y)^3]/(d(x^2+y))*[d(x^2+y)]/dxy2dxdx+xdy2dx=d(x2+y)3d(x2+y)d(x2+y)dx

Using sum rule to evaluate [d(x^2+y)]/dxd(x2+y)dx & chain rule to evaluate dy^2/dxdy2dx

=> y^2 + x*dy^2/dy*dy/dx = [3*(x^2+y)^2]*[dx^2/dx + dy/dx]y2+xdy2dydydx=[3(x2+y)2][dx2dx+dydx]

=> y^2 + x*2y*dy/dx = 3(x^2+y)^2*[2x+dy/dx]y2+x2ydydx=3(x2+y)2[2x+dydx]

=> y^2 + 2xy*dy/dx = 6x(x^2+y)^2 + 3(x^2+y)^2*dy/dxy2+2xydydx=6x(x2+y)2+3(x2+y)2dydx

=> 2xy*dy/dx - 3(x^2+y)^2*dy/dx = 6x(x^2+y)^2 - y^2 2xydydx3(x2+y)2dydx=6x(x2+y)2y2

=> [2xy - 3(x^2+y)^2]*dy/dx = 6x(x^2+y)^2 - y^2[2xy3(x2+y)2]dydx=6x(x2+y)2y2

=> color(red){dy/dx = [6x(x^2+y)^2 - y^2]/[2xy - 3(x^2+y)^2]}dydx=6x(x2+y)2y22xy3(x2+y)2