Why isn't the first one true?

Step-by-step explanation:
The integral represents the area under a curve. You can think of it as a sum. Just because the sum of f(x) is greater than the sum of g(x), does not mean that each f(x) term is greater than the corresponding g(x) term.
For example, 3 + 2 + 1 = 6, and 1 + 3 + 1 = 5. The first sum is greater than the second sum, but the middle term in the first sum (2) is less than the middle term of the second sum (3).
Answer:
I. requires a function relationship everywhere that may not exist.
Step-by-step explanation:
The integral gives the area under the curve. It says nothing about the function value, except on average.
Consider the case where [a, b] = [0, 10] and ...
g(x) = -0.1
f(x) = -2 + 25·δ(x)
(The impulse function δ(x) has unit area and is zero everywhere except x=0.)
In this scenario, the only place where f(x) > g(x) is at x=0.