Exponential Growth and Decay Formulas

Steps for Exponential Problem Solving

1: Decide if the problem is describing exponential growth or decay. ("increase" = growth, "decrease" = decay)

2: Convert the growth or decay percentage to a decimal. This decimal is your r value. Ex: 23% = .23 and 5% = .05

3: Write your exponential equation. a is your starting value.

GROWTH: y = a(1 + r)^x

DECAY: y = a(1 - r)^x

4: Use the equation to solve the problem. Remember that x is input and y is output.