Question

Let f(x) =5x-1, h(x)= -x+5.
Find (h of)(3).
(hof)(3)

Answer 1

(h ◦ f)(x) is the composition of h(x) with f(x),

(h ◦ f)(x) = h(f(x))

which we can compute by simplying replacing in h(x) every instance of x with f(x) itself:

(h ◦ f)(x) = h(f(x))

(h ◦ f)(x) = h(5x - 1)

(h ◦ f)(x) = -(5x - 1) + 5

(h ◦ f)(x) = -5x + 1 + 5

(h ◦ f)(x) = -5x + 6

Then

(h ◦ f)(3) = -5 • 3 + 6

(h ◦ f)(3) = -15 + 6

(h ◦ f)(3) = -9