THT 10, not the hardest (Curved to 17)

Typos:

1A: it should say that the min are +/- 2, not a max. Vice versa for the x=0. I mean, i even did the number line correctly so i'm not sure how that happened.

2C: I butchered the explanation, it should say something like "its concave up because the slope of the f'(x) graph is positive" or something among those lines (not exactly sure what happened when I was making the key lol)