Question

what is 16x^4-81

Answer 1

Factor?

Answer 2

yes

Answer 3

(4x^2+9)(2x+3)(2x-3)

Answer 4

Why did it have 3 parenthesis in the answer

Answer 5

a² - b² = (a+b)(a-b)

Answer 6

I can't really give you a good explanation for the parenthesis. I just factored and that's what I got. I'm positive that is the answer.

Answer 7

thanks

Answer 8

You are very welcome :)

Answer 9

\[
16x^4-81 = (4x^2)^2 - (9)^2 \\
\text{Use the identity: }a^2-b^2 = (a+b)(a-b) \\
(4x^2)^2 - (9)^2 = (4x^2+9)(4x^2-9) = (4x^2+9) * \{~(2x)^2-3^2 ~\} \\
\text{Again use the identity: }a^2-b^2 = (a+b)(a-b) \\
(4x^2+9) * \{~(2x)^2-3^2 ~\} = (4x^2+9) * (2x+3)*(2x-3)\\\\
\]