Answer
$25-9x^2$
Work Step by Step
RECALL:
$(a+b)(a-b)=a^2-b^2$
Use the formula above with $a=5$ and $b=3x$ to obtain:
$(5+3x)(5-3x)
\\=5^2-(3x)^2
\\=25-9x^2$
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.