Question

How do you use the difference of two squares formula to factor `4x^2 − 81`?

Answer 1

The geeral form for the difference of squares is
#a^2-b^2)=(a+b)(a-b)

For the given example
`4x^2 -81`

`= (2x)^2 - 9^2`

`= (2x+9)(2x-9)`