Question

What is the final result of factoring:
81a^2-49

(I know that the squares of 81 is 8 and 49 is 7 but not sure what my finished product should look like)

Answer 1

\(\bf 81a^2-49\implies 9^2a^2-7^2\implies (9a)^2-7^2
\\ \quad \\
recall \implies {\color{brown}{ a^2-b^2 = (a-b)(a+b)}}\)

Answer 2

so the answer is: (9a-7)(9a+7)

Answer 3

yeap

Answer 4

thank you