factor the third denominator. Then note that the least common denominator will be p(p - 3).
Convert the three fractions to this common denominator, and then add and subtract the numerators.
Then simplify the result, if possible, by factoring the numerator and seeing if anything cancels.
If you get stuck, please reply showing your work, either using LaTeX or else using standard web-safe formatting to make your meaning clear. Your work will probably start something like:
. . . . .
And the next step...
This makes your LCD =
Looking at it a little differently than the others, try multiplying this LCD by each term in your expression, cancelling appropriately as you go. By doing this, you create your new numerator.
Expand and combine terms and place this over
Just a variation on a theme.
I understand what you are saying. Really, I do.
The only contribution I wanted to make here is that if you want to find a new numerator given a different denominator (LCD), then you can do what I just demonstrated. It's just a technique.
For instance, say, you need to convert to , you would just multiply by to get . And that's your new numerator.