Use the intermediate value theorem to show that the polynomial has a real zero between the given integers?

Question

f(x)= x^3-x-4; between 1 and 7

Answer 1

Plug 1 into f(x): f(1)=1^3-1-4

Then plug 7 in to f(x): f(x)=7^3-7-4

If one of them gives you a positive answer and the other gives a negative, that means the line that connects them MUST cross the x axis to switch from negative to positive (or vice versa)