Exercise 8 Page 250

We are asked to find what number is not part of the domain of the function. We almost must explain how can we tell. Recall that the domain is all values that the variable $x$ can take. When our functions are fractions we need to be careful that the value of the denominator does not become zero, because that makes the fraction undefined. To see when our denominator becomes zero we can solve for $x-1=0.$ As we can see, the denominator becomes zero when $x=1.$ Therefore, $1$ is not part of the domain of the function.