Question

How do you find the product of `(3a-4)(3a+4)`?

Answer 1

The result is `9a^2 - 16`

The reason is the following:

The problem is an example of a notable product: "the sum multiplied by the diference is equal to the difference of squares", that is to say: `(a+b)·(a-b) = a^2-b^2`.
By applying this to our question, we obtain that:
`(3a-4)·(3a+4) = (3a)^2-(4)^2 = 9a^2 - 16`.