I need help simplifying a rational expression.

When simplifying a rational expression, why do you need to factor the numerator and the denominator?

• When simplifying a rational expression, why do you need to factor the numerator and the denominator? B. When adding and subtracting rational expressions, why do you need a LCD? C. When a polynomial is not factorable what is it called? Why?

• Answer:

  1. If any factor is divisible into both the numerator and denominator, you can cancel it out (as long as it doesn't equal zero). 2. You need any common denominator, because you can add or subtract things that are different, i.e. what's one inch plus one centimeter? You need to first convert into common units or denominators. You don't have to use the LOWEST common denominator, but that's usually easier than a bigger one, because it's a smaller number. 3. Prime.