calculus - math

Question

In the following intervals put a + if the derivative of f is positive or put a − if the derivative of f is negative.

Interval:

(−∞, −2.6)

(−2.6, −1.1)

(−1.1, 0.2)

(0.2,∞)

Answer 1

Inspect the given graph of f: f^'(x) (i.e. its derivative) is - whenever f is decreasing (reading left to right) and + whenever f is increasing.