8th Grade Algebra
posted by Gretchen .
(b^210b+21)/(b^211b+28)
I need help trying to figure out how to factor each quantity or parentheses.
and then simplifying it.

For (b^210b+21), start with listing the factors that multiply to give 21.
1,21
3,7
7,3
21,1
As 21 is positive and 10b is negative, you will find that the factors are in the following form:
(bx)(by)
where x and y are chosen from the pair of factors. If you multiply out the factors, you will get
(bx)(by)=b^2(x+y)b+xy
Thus, you will choose from the list of factors a pair which will give
xy=21 and x+y=10.
Try the same for the denominator. It has more factors, so the list of factors will look like:
1,28
2,14
4,7
7,4
14,2
28,1
The method to follow is exactly the same as the numerator.
Tell us what you found.