# Rational expressions

• Oct 3rd 2007, 04:39 PM
aikenfan
Rational expressions
I did a few more of these types of problems...could someone please take a look at them...I would like to make sure that I am doing the correctly...
http://i103.photobucket.com/albums/m...919/111002.jpg
• Oct 3rd 2007, 05:25 PM
topsquark
Quote:

Originally Posted by aikenfan
I did a few more of these types of problems...could someone please take a look at them...I would like to make sure that I am doing the correctly...
http://i103.photobucket.com/albums/m...919/111002.jpg

You really need to work on using parenthesis. For example in 7 you have [tex]2x + 1(x + 1)[tex] instead of $(2x + 1)(x + 1)$. You have a similar error in 8 and 14. (This, in fact, caused your answers to 8 and 14 to be incorrect.)

In 11, $-3(x - 1)$ is equal to what?

The rest looks good.

-Dan
• Oct 3rd 2007, 05:45 PM
aikenfan
For number 8, I now get: (2x^2 + 4)/ (x-2)(x+2)
For number 14, I get (-7x^2 + 65x + 372)/(x + 4)(x - 3)
• Oct 3rd 2007, 05:56 PM
topsquark
Quote:

Originally Posted by aikenfan
For number 8, I now get: (2x^2 + 4)/ (x-2)(x+2)

$(x^2 + 4x + 4) + (x^2 - 4x + 4) =$?

Quote:

Originally Posted by aikenfan
For number 14, I get (-7x^2 + 65x + 372)/(x + 4)(x - 3)

Yes, but it is not simplified. The numerator factors.
(By the way, you could've simplified the first term in the original problem.)

-Dan
• Oct 3rd 2007, 06:05 PM
aikenfan
The numerator for 8 is 2x^2 + 8
• Oct 3rd 2007, 06:07 PM
aikenfan
93 and -28 multiply to get -2604 and add to get 65...im a little confused...what do I do with that now?
it would be (x + 93)(x - 28)?
• Oct 3rd 2007, 06:10 PM
topsquark
Quote:

Originally Posted by aikenfan
For number 8, I now get: (2x^2 + 4)/ (x-2)(x+2)
For number 14, I get (-7x^2 + 65x + 372)/(x + 4)(x - 3)

Quote:

Originally Posted by aikenfan
93 and -28 multiply to get -2604 and add to get 65...im a little confused...what do I do with that now?

The hint is that there is a cancellation in your answer. So think of it this way instead: does $-7x^2 + 65x + 372$ contain a factor of either $x + 4$ or $x - 3$?

-Dan