Rational Expressions

by Anthony
(Meriwether)




1. Find all numbers for which the rational expression is undefined...

5/v-6


2. Divide and simplify...

f+4/f-1 divided by 7f+28/f-6


Comments for Rational Expressions

Average Rating starstarstarstarstar

Click here to add your own comments

Jul 02, 2010
Rating
starstarstarstarstar 		Rational Expressions
by: Karin

1. Find all numbers for which the rational number is undefined. 5/v-6

A rational number is undefined when the denominator is 0. Therefore, in this rational expression, if we substituted 6 for v, we would end up with 0 in the denominator. If v = 6, the rational number will be undefined.


2. Divide and simplify:
( f + 4/f-1) / (7f+28/f-6)

Remember that when you divide rational expressions, you actually multiply by the reciprocal.

Therefore, we would rewrite this expression as:
f + 4 f-6
------ * ------
f-1 7f + 28

Now we multiply:

f + 4 f-6 (f+4) (f-6)
------ * ------ = ----------
f-1 7f + 28 (f-1) 7(f+4)

**I factored 7f + 28, by factoring out the 7. When you divide both terms by 7, you end up with:
7 (f+4).

Now we have:
(f+4) (f-6) f-6
------------ = -----
(f-1) 7(f+4) 7(f-1)

Since (f=4) is in the numerator and denominator, we can simplify those terms to 1. We are left with f-6 in the numerator and 7(f-1) in the denominator.

I hope this helps,
Karin

Click here to add your own comments

Join in and write your own page! It's easy to do. How? Simply click here to return to Students.

Need More Help With Your Algebra Studies?

Get access to hundreds of video examples and practice problems with your subscription! 

Click here for more information on our affordable subscription options.

Not ready to subscribe?  Register for our FREE Pre-Algebra Refresher course.