# Week 15 – Precalc 11

This week in precalc 11 we learned more about rational expressions and solving. We learned adding and subtracting rational expressions. We also learned how to solve rational equations.

When solving rational expressions, there are three methods you can use
1) Converting to a common denominator: you just multiply both sides of the equation by the common denominator, with this you can eliminate the denominators and turn the rational equation into a polynomial equation.

2) Multiplying through by the common denominator: we convert everything to the common denominator and then compare numerators

3) Cross multiplying: this works only if the equation has exactly one fraction on one side of the equal sign set exactly one fraction on the other side of the equals

When adding/subtracting rational expressions:
-find non-permissible values
-factor (if needed)
-cross out things that are the same or equivalent

-find common denominator
-multiply the fraction to get the common denominator
-add or subtract the numerators