Pre-Algebra
Algebra 1
Factoring Quadratics
Algebra 1$$ax^2 + bx + c = (px + q)(rx + s)$$
Quadratic Formula
Algebra 1$$x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$$
Slope Formula
Algebra 1$$m = \frac{y_2 - y_1}{x_2 - x_1}$$
Slope-Intercept Form
Algebra 1$$y = mx + b$$
Distance & Midpoint
Algebra 1$$d = \sqrt{(x_2-x_1)^2 + (y_2-y_1)^2}$$
Simple & Compound Interest
Algebra 1$$A = P\!\left(1 + \frac{r}{n}\right)^{nt}$$
Calculus
Finance
Percent Change
Finance$$\%\,\text{change} = \frac{\text{new} - \text{old}}{|\text{old}|} \times 100$$
Return on Investment (ROI)
Finance$$ROI = \frac{\text{gain} - \text{cost}}{\text{cost}} \times 100$$
Rule of 72
Finance$$t \approx \frac{72}{r}$$
Break-Even Point
Finance$$Q = \frac{FC}{P - VC}$$
Present & Future Value
Finance$$FV = PV\,(1 + r)^t$$
Future Value of an Annuity
Finance$$FV = PMT \cdot \frac{(1+r)^n - 1}{r}$$
Loan Payment
Finance$$M = P \cdot \frac{r(1+r)^n}{(1+r)^n - 1}$$