Answer:
2 is not in the domain of f of g
Explanation:
* Lets revise at first the meaning of f of g (composite function)
- A composite function is a function that depends on another function
- A composite function is created when one function is substituted into
another function
- Example:
# f(g(x)) is the composite function that is formed when g(x) is
substituted for x in f(x).
- In the composition (f ο g)(x), the domain of f becomes g(x)
* Now lets solve the problem
∵ f(x) = 4x + 3
∵ g(x) = √(x - 9)
- Lets find f(g(x)), by replacing x in f by g(x)
∴ f(g(x)) = f(√(x - 9)) = 4[√(x - 9)] + 3
∴ f(g(x)) = 4√(x - 9) + 3
∵ The domain of f is g(x)
- The domain of the function is the values of x which make the
function defined
∵ There is no square root for negative values
∴ x - 9 must be greater than or equal zero
∵ x - 9 ≥ 0 ⇒ add 9 for both sides
∴ x ≥ 9
∴ The domain of f of g is all the real numbers greater than or equal 9
∴ The domain = {x I x ≥ 9}
∵ 2 is smaller than 9
∴ 2 is not in the domain of f of g