# mat 117/algebra

posted by
**Diana**
.

Find a value for k so the 9m^2-kn^2 will have the factors 3m + 7n and 3m -7n. Please show me how to get this and show the work please.

Use that (a-b)(a+b) = a^2 - b^2

So, you can read-off that k = 49.