factor

9m^2 - 64n^2

The given expression, 9m^2 - 64n^2, is a difference of squares.

So, we can factor it using the formula:
a^2 - b^2 = (a + b)(a - b)

In this case, a = 3m and b = 8n.
Therefore, we can factor 9m^2 - 64n^2 as:
(3m + 8n)(3m - 8n)