Please help: calculus prob

Question

The graph of the derivative, f '(x) is shown below. On what interval is the graph of f (x) concave up?

Option:

1. Concave up on (-∞, -1)
2. Concave up on (-∞, -∞)
3. Concave up on (-1, ∞)
4. Concave up on (-6, -2)

Answer 1

The graph of f(x) will be concave up when the 2nd derivative f"(x) is positive. Since you are given f'(x), you want to find the part of the graph of f'(x) where its rate of change is positive (sloping up as you move from left to right. Yes, f'(x) is curved ... so think of the tangent line at each point).

#3