Pre-Calculus 11 Week 10 – Midterm Review!

Our midterm is next week! So for this post, I’ll review one of the units that I had more trouble with. Absolute Values and Radicals. More specifically, rationalising fractions that have binomials as a denominator. Such as…

\frac{3\sqrt{8}+\sqrt2{5}}{\sqrt{2}+\sqrt{20}}

To rationalise a fraction means to make sure that there is no radical in the denominator. In the case that there’s a binomial as the denominator, you still multiply by the conjugate. The conjugate in this case will be a binomial, \frac{\sqrt{2}-\sqrt{20}}{\sqrt{2}-\sqrt{20}}. Multiplying the denominator by it’s conjugate eliminates the “middle term” that it usually creates. This creates a denominator with no radicals! Proof is below… (Excuse my handwriting)