Use limits to find the area between each curve and the x axis for the given interval.

1. y=(x^2+6x) from x=0 to x=4

I found delta x being 4/n and xi=4i/n

Then I plug it in

(4i/n)^2+6(4i/n) times (4/n)

I am stuck here because I see I am supposed to add but I am slightly confused in getting like term if anyone could work this part out be helpful.

(16i/n^2)+24i/n times 4/n (This is where I am stuck)