Reflection over x-axis
hope that helps
1.4km 1000 meters is equal to 1 kilometer
The critical points are at x = 1 and x = 4 giving you the intervals (-inf, 1), (1, 4) and (4, inf).
By substituting x values in these 3 intervals, you can see that f'(x) is positive in the first and third intervals and negative in the second interval.
This means that f(x) is increasing in the first and third intervals and decreasing in the second interval.
The answer is D.
You just have to plug in the numbers and solve
7(-2)(-15)
7(30)
210
