Question

What is the factored form of the expression?

4x^2 – 81y^2
A. (2x + 9)(2x – 9)
B. (2x + 9y)(2x – 9y)
C. (2x + 9y)2
D. (2x – 9y)2

Answer 1

This is a difference of squares.

Answer 2

\(\Large \color{MidnightBlue}{\Rightarrow a^2 - b^2 = (a + b)(a - b) \Longleftrightarrow (2x)^2 - (9y)^2 = (2x + 9y)(2x - 9y) }\)

Answer 3

*

\(\Large \color{MidnightBlue}{\Rightarrow (2x + 9y)(2x - 9y) }\)