An equation connecting?x?and?y?is not always easy to write?explicitly?in the form?y=?f(x)?or?x?=?f(y)
However you can still differentiate such an equation?implicitly?using the?chain rule:
Combining this with the?product rule?gives us:
These two special cases are especially useful:
When?x?and?y?are connected in an?equation?you can differentiate both sides with respect to?x?and rearrange to find a formula (usually in terms of?x?and?y?) for?dy/dx
Note that?dy/dx?is a single algebraic object
When rearranging do not treat?dy/dx?as a fraction
Especially do not try to separate?dy?and?dx?and treat them as algebraic objects on their own!
Exam Tip
When using implicit differentiation you will not always be able to write?dy/dx?simply as a function of?x.
However, this does not stop you from answering questions involving the derivative.