How would this multiply out so it can be differentiated?

also

Iv found the two factors are x+1 and x-4 but does this mean the limit is x+1 and x-4 or x-1 and x+4?Code:`Find the line enclosed between the curve`

and the line

Thanks in advance ;)

edit : unfortunetly i have another tiny small problem :D

How would i simplify this?