Simplifying Rational Expressions: x2+7x+10/x2+11x+18  TOPIC_SOLVED

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Simplifying Rational Expressions: x2+7x+10/x2+11x+18

Postby leahlou on Sat Jan 17, 2009 4:05 am

Hi everyone, my name is Leah and I'm taking an online College Algebra course at WCJC. I just need help understanding this question :confused: . Anything would be helpful. :D

Simplify the rational expression. Find all the numbers that must be excluded from the domain of the simplified rational expression.

x2 + 7x + 10/
x2 + 11x + 18

What i don't understand is the last part of the question, finding all the numbers that must be excluded. I know how to simplify rational expressions. :) Also it's multiple choice, so that kind of narrows it down, I just want to understand this.
Thanks.
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Re: Simplifying Rational Expressions  TOPIC_SOLVED

Postby DAiv on Sat Jan 17, 2009 12:51 pm

leahlou wrote:Simplify the rational expression. Find all the numbers that must be excluded from the domain of the simplified rational expression.

x2 + 7x + 10/
x2 + 11x + 18

What i don't understand is the last part of the question, finding all the numbers that must be excluded. I know how to simplify rational expressions. :) Also it's multiple choice, so that kind of narrows it down, I just want to understand this.
Thanks.


Hi Leah, the section on Rational Expressions: Finding the Domain should help you understand this.

In a nutshell, however, they're asking for what value (or values) of would cause the denominator (the bottom half) of the simplified expression to equal zero and thus cause a 'division by zero', which is not allowed.


Also, the section on how to type math clearly will show you how to layout equations so that they appear correctly:




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Postby stapel_eliz on Sat Jan 17, 2009 6:26 pm

leahlou wrote:Simplify the rational expression....

x2 + 7x + 10/
x2 + 11x + 18

To do the simplification on your own (that is, when there aren't multiple-choice options whose graphs you can compare), reduce this fraction just like you'd reduce any numerical fraction: Find the common factors, and divide them out (or, if you prefer, "cancel" them off).

Note: This requires that you know how to factor quadratics!

Have fun! :D

Eliz.
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