Question

If one of the factors of r ^ 2 + 21r + 98 is r + 7 , what is the other factor?

Answer 1

Answer:

i think factor the expression (r+7)(r+14) is answer

Step-by-step explanation:

Answer 2

Answer:

(r + 14)

Step-by-step explanation:

When factoring a trinomial in the form of:

$ax^2+bx+c$

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:

$r^2+21r+98\\r^2+7r+14r+98$

Finally, you can factor each half of this individually.

$(r^2+7r)+(14r+98)\\r(r+7)+14(r+7)\\(r+14)(r+7)$

We were already given (r + 7), so the answer is (r + 14).