Question

How do you factor `r^2-9t^2`?

Answer 1

`(r+3t)(r-3t)`

Explanation:

The problem is a difference of squares. In general, `a^2-b^2` factors to `(a+b)(a-b)`, in this case `a` is `r` and `b` is `3t`.

See the link below for a more in-depth instruction
http://www.mesacc.edu/~scotz47781/mat120/notes/factoring/diff_of_squares/diff_of_squares.html