Question

Let f(x)=1/x and g(x)=x^2-7x what two numbers are not in the domain of f °g?

Answer 1

x ∈ {0, 7} are not in the domain

Explanation:

f(x) is undefined for x=0, so f(g(x)) will be undefined for g(x) = 0.

We are looking for the values of x that make g(x) = 0. They are the solutions to ...

x^2 -7x = 0

x(x -7) = 0

This product will be zero when either factor is zero, for ...

x = 0 . . . or . . . x = 7

The domain of f(g(x)) excludes x=0 and x=7.