Answer
$d(x)=x-x^2-2$ with domain all real numbers.
$d(-1)=-4$
Work Step by Step
$f(x)=x^2+1$
$g(x)=x-1$
$d(x)=x-1-(x^2+1)=x-1-x^2-1=x-x^2-2$
The domain of $f(x)$ and $g(x)$ is all real numbers, so that will be the domain of $d(x)$ too.
$d(-1)=-1-(-1)^2-2=-1-1-2=-4$
