Factor.

125r^2-245

= 5(25r^2 - 49)

= 5(5r+7)(5r-7)

To factor the expression 125r^2 - 245, we can look for the common factors between the two terms. In this case, there is no common factor between 125r^2 and 245 that can be factored out.

However, we can still factor the expression by noticing that both terms are divisible by 5. By factoring out 5, we get:

5(25r^2 - 49)

Now, let's focus on factoring the expression 25r^2 - 49. We notice that it can be written as the difference of squares. The square root of 25r^2 is 5r, and the square root of 49 is 7. So, the expression can be factored as:

5(5r + 7)(5r - 7)

Therefore, the fully factored form of 125r^2 - 245 is 5(5r + 7)(5r - 7).