I need to approximate int((1/3*x^2+2) dx) on the interval [1, 9] using a left Riemann sum, and 4 rectangles of equal base.

I'm having trouble graphing it, I've used my calculator to see what it looks like but if I try to graph it by hand it won't be as perfect and the rectangles wouldn't fit under the curve. The graphing part is really stressing me out.

Would the 1st endpoint be at 2/3? by plugging in 1 into $\displaystyle (1/3*x^2)$ and the 2nd be 27 by plugging in 9?

Each rectangle's... width would be 2...

something like that?