Functions with Unknown Constants: If f(x)=ax^2-x and f(4)=28, what is f(-2)?

1. Solve for the unknown, in this case "a"
2. Rewrite the function. replacing the constant with numerical value.
3. Solve function for the new input variable.

Common Function Type #1: Direct Proportionality - Set up ratios for the "before" case and the "after" case, and then set the ratios equal to each other.

Common Function Type #2: Indirect Proportionality - Set up products for the "before" case and the "after" case, and then set the products equal to each other.