Question

Factor completely 4x2 - 81.
(4x - 9)(x + 9)
(2x + 9)(2x + 9)
(2x + 9)(2x - 9)
(2x - 9)(2x - 9)

Answer 1

I don't understand what you are trying to do here. Are you trying to get the answer for each math problem?

Answer 2

no this isn't even on the same thing

Answer 3

apply difference of square method \[\huge\rm (a^2 - b^2) = (a-b)(a+b)\]

Answer 4

so its (2x+9)(2x-9)

Answer 5

that's what I thought but I don't wanna get it wrong

Answer 6

how ??

Answer 7

because a negative times a positive is a negative and 4x times x is 4x^2

Answer 8

take square root of first term and take square root of 2nd term
one parentheses should be negative and one should be positive