There are three things you have to know:
- A function is convex when its second derivative

- A function is concave when it second derivative

- The derivative of a power,
, is 
So, the first derivative is

and the second derivative is

This implies that the second derivative of a parabola is constant, and of course that 2 doesn't change the sign of
.
7/12 of 1 hour:
1 hour = 60 min.
7/12 * 60
7 * 5 = 35
Francis ran 2 1/2 miles in 35 min.
2 1/2 = 5/2
5/2 miles = 35 min
x miles = 60 min
(Cross Multiply)
5/2 * 60 = 35x
5 * 30 = 35x
150 / 35 = x
x = 30 / 7 = 4 2/7 miles
Francis ran 4 2/7 miles in one hour.
(6×30)×3 is the answer to this equation please reward brainlest