PART A:
In order to calculate (fog)(x), that is, f(g(x)), we need to use g(x) as the input value (value of x) of f(x).
So we have:
[tex]\begin{gathered} f(x)=\frac{1}{2}x-7 \\ f(g(x))=\frac{1}{2}g(x)-7 \\ f(g(x))=\frac{1}{2}(2x+14)-7 \\ f(g(x))=x+7-7 \\ f(g(x))=x \end{gathered}[/tex]
PART B:
Let's use f(x) as the input value of g(x):
[tex]\begin{gathered} g(x)=2x+14 \\ g(f(x))=2f(x)+14 \\ g(f(x))=2(\frac{1}{2}x-7)+14 \\ g(f(x))=x-14+14 \\ g(f(x))=x \end{gathered}[/tex]
PART C:
When two functions are inverse to each other, we have the following property:
[tex]f(f^{-1}(x))=f^{-1}\mleft(f\mleft(x\mright)\mright)=x[/tex]
Since the composite functions of f(x) and g(x) are equal to x, therefore f(x) and g(x) are inverse functions.