Answer:
(r + 14)
Step-by-step explanation:
When factoring a trinomial in the form of:
[tex]ax^2+bx+c[/tex]
you need to find 2 numbers that multiply to make ac and add to make b. Here, we need to find 2 numbers that multiply to 98 and add to 21. First, list the factors of 98:
1, 98
2, 49
7, 14
and the reverse of all of those is also true.
Now find factors that add to 21. In this case, those are 7 and 14. You need to break the middle term in the trinomial into those 2 numbers:
[tex]r^2+21r+98\\r^2+7r+14r+98[/tex]
Finally, you can factor each half of this individually.
[tex](r^2+7r)+(14r+98)\\r(r+7)+14(r+7)\\(r+14)(r+7)[/tex]
We were already given (r + 7), so the answer is (r + 14).
