Exercise 4 Page 293

We can check our answer by substituting the given zeros for $x.$ If the result is $f(x)=0,$ it means that the given numbers are actually zeros of the function and our answer is correct. Let's start by checking $\text{-}1.$ We proved that $\text{-}1$ is a zero of the function. Let's now check $1.$ We have shown that $1$ is also a zero. Finally, let's see what happens with $0.$ We found that $0$ is also a zero. Since $\text{-}1,$ $1$ and $0$ are zeros of the polynomial function, our answer is correct.