I am working on a mix/max problem and am stuck.

within the interval of [-1,4]. The exponent of e is , can't get Latex to cooperate with me.

Using the product rule to differentiate and I get:

y'=

Factor out the and I get

For all real numbers, the 2nd term will never equal 0, so the only one that can equal 0 is .

I don't know how to solve for x when . Any pointers?