# 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

Average Rating     Jul 02, 2010 Rating     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 Need More Help With Your Algebra Studies?