PreCalculus I

Video 1 of 3: Rational Expressions

$\frac{ac}{bc}=\frac{a}{b}$

$\frac{a}{b}\cdot\frac{c}{d}=\frac{ac}{bd}$

$\frac{a}{b}\div\frac{c}{d}=\frac{a}{b}\cdot\frac{d}{c}$

$\frac{a}{c}+\frac{b}{c}=\frac{a+b}{c}$

The conjugate radical of $a+b\sqrt{c}$ is $a-b\sqrt{c}$ and holds the property that when two conjugates are multiplied, a rational number is created:

$(a+b\sqrt{c})(a-b\sqrt{c})=a^2-b^2c$

1.3 – Quiz