OK guys I have this problem  :

For $x,y,p,q>0$ and $ \frac {1} {p} + \frac {1}{q}=1 $ prove that $ xy \leq\frac{x^p}{p} + \frac{y^q}{q}$

It says I should use Jensen's inequality, but I can't figure out how to apply it in this case. Any ideas about the solution  ?

OK guys I have this problem:

For $x,y,p,q>0$ and $ \frac {1} {p} + \frac {1}{q}=1 $ prove that $ xy \leq\frac{x^p}{p} + \frac{y^q}{q}$

It says I should use Jensen's inequality, but I can't figure out how to apply it in this case. Any ideas about the solution?