To Baltair: THANK YOU ESPECIALLY! ( you explained it really well) essentially I confused the chain rule with something else)

All the other answers are so long, so read mine and be happy and go eat cake or something.

1. Find the derivative of f(x)...easy as pie. Actually no, I lied...pie is pretty hard. Easy as cake.
2. You now have the equation of the slope of f(x)...f'(x)
3. You want to know when f(x) is increasing....therefo re the slope f'(x) has to be positive.
4. Sub the values of x into f'(x). The number that give a positive value for f'(x) is the answer
5. Go eat cake

Spoiler: (Highlight the grey box to see the hidden message.)

The cake is a lie.