Answer
Domain of\[f=\left\{ x|x\ne 5,x\ne -4 \right\}\]
Work Step by Step
Division by zero is undefined, so, exclude from the domain each function value of x.
The denominator of $g\left( x \right)=\frac{3{{x}^{2}}}{\left( x-5 \right)\left( x+4 \right)}$ is 0 if $x=5$ and $x=-4$
Thus, x cannot be 5 and -4.
Domain of $f=\left\{ x|x\ne 5,x\ne -4 \right\}$.
