Question

The graph shows the number of good deeds performed at a fast food drive thru over the course of a weekend. Customers were "paying it forward" by purchasing a food item for the person behind them in line. Write the exponential function rule and equation, please

Time (x) to Number of Good deeds (y)

0 to 2
1 to 6
2 to 18

Answer 1

Use the form y = a·b^x.

At x = 0, y = a = 2. The growth factor b = 6/2 = 3 (also 18/6 = 3).

So the exponential rule is y = 2·3^x (or f(x) = 2·3^x).

Check: x=1 → y=2·3=6; x=2 → y=2·9=18.