Formulas that are used many times. Usually.

This may not be usable depending on if you're smarter than me or not.

Pythagorean Theorem
a² + b² = c²	It's used to find the hypotenuse of a right triangle. c is always the hypotenuse.

Quadratic Formula
	Commonly used in expressions or inequalities, It is used to get past a seemingly impossible roadblock where you think you have fully simplified the expression. a also must be nonzero.

Newton's Second Law
	force equals mass times acceleration. if you need this, you probably understand it. if you remember nothing like me, it's basically: force is equivalent to mass, when multiplied by acceleration. this can be used when you need to calculate force, mass, or acceleration. it's very simple.

The Perfect Square Trinomials
	Actually pretty helpful. You use it where you expect to use it. Any place that seems like it could be simplified, but seems impossible, and also has two variables added together and squared. Pretty specific, but comes up often.