Explanation
The domain of a function is the set of all possible inputs(x) for the function, and the range is the set of outputs
Step 1
find y
[tex]\begin{gathered} f(x)=x^2-6x \\ f(x)=x(x-6) \\ y=x(x-6) \\ a)\text{ when x =-7} \\ f(-7)=-7(-7-6)=-7\cdot-13=91 \\ f(-2)=-2(-2-6)=-2\cdot-8=16 \\ f(1)=1(1-6)=1\cdot-5=-5 \\ \\ \end{gathered}[/tex]then, the range is
[tex]\lbrace91,16,-5\rbrace[/tex]