2  Derivatives of implicit functions
Until now we have been differentiating various functions given in the form y = f(x) But it is not necessary that functions are always expressed in this form For example,
consider one of the following relationships between x and y:
x – y – π = 0
x + sin xy – y = 0
In the first case, we can solve for y and rewrite the relationship as y = x – π In
the second case, it does not seem that there is an easy way to solve for y