Daniel B. answered 12/09/20
A retired computer professional to teach math, physics
The function g(x) is the area under the curve of f between 0 and x.
(a) Starting from 0, that area keeps increasing until x=2,
at which point the area starts decreasing.
Then at x=4 the area starts increasing again.
Therefore the local maxima and minima of g(x) are at x=2, x=4, x=6, x=8.
(b) The function g is concave down where its derivative, f, is decreasing.
That is on the intervals [1,3], [5,7], [9,8].