Question

How do you factor the polynomials `rp-9r+9p-81`?

Answer 1

`(r+9)(p-9)`

Explanation:

To factor, you need to find like terms. The like terms in this expression are 9, p, and r. If you notice how the expression is written, you see that r is a common in the first two terms. 9 is common in the second two terms. Let's factor out r from the first two terms and 9 from the second two terms.

`rp-9r+9p-81 ->`

`r(p-9)+9(p-9)`

Now we have `(p-9)` as the common term. We can factor out `(p-9)` to get the factored form of the whole expression.

`r(p-9)+9(p-9) ->`

`(p-9)(r+9)` OR `(r+9)(p-9)`

If you want to check your answer, you can FOIL it or plug in two random numbers for r and p.