Friday, October 30, 2009

Rational Expressions: Excluded Values & Simplifying

No post yesterday. It was just the quiz.

Today, we worked with rational expressions. Rational expressions are expressions that can be written as a fraction. However, even when the fraction is made with polynomials, we have to remember that the denominator cannot equal 0. So, we have to list any exclude values.

Example: Find the excluded values from the following rational expression.
  1. Set the denominator equal to zero: 25u2 - 36 = 0
  2. Solve the equation to find the excluded values. Look back at Tuesday's notes to remember how to solve by factoring.
Here: (5u - 6) (5u + 6) = 0
So, 5u - 6 = 0 or 5u + 6 = 0
5u = 6 5u = -6
u = 1.2 or u = -1.2
Excluded Values: 1.2 and -1.2

We also discussed how to simplify rational expressions. This concept was taught last Friday, so today's lesson reviewed and reinforced that previous understanding.

Homework: Page 163, #2 - 14 even and #19; Page 164, #3 - 8 and #11 - 13

There will be a test next Friday covering ALL of unit 2: Radicals, Polynomials, Factoring, & Rationals.



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