Answer
$27$
Work Step by Step
Recall that if $f$ is a polynomial, then $\lim_\limits{x\to a}f(x)=f(a)$. Thus, we can find the limit by plugging $a$ into the function and simplifying: $$\lim_\limits{x\to4}(6x-21)^3=(6(4)-21)^3=3^3=27$$
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.