First, we need to define the function of (fog)(x) (fog)(x) = f(g(x)) it means we need to substitute the x in the function f(x) with g(x)
f(x) = x + 7 change x with g(x) fog(x) = g(x) + 7 fog(x) = + 7
equalize the denominators fog(x) = + 7 fog(x) =
simplify fog(x) = fog(x) =
Second, determine the domain of the function If the function is in fraction form, the denominator of the fraction can't be equal to zero. x - 13 ≠ 0 x ≠ 13 The domain is {x| x≠13} The answer is last option