Question

Question in screenshot

Answer 1

think about it this way...

how high does it rebound to after 1 bounce..?

in the formula n is the number of bounces...

there is no zero bounce

Answer 2

To add up to campbell answer:
Try to imagine, how you would count the max height of a ball after one bounce. It would be 20(.75), how about, after two bounces? 20(.75)(.75) And it works for all other numbers as well! Can you make up something out of this? (Remember how you write continuous multiplication in a shorthand way)

Answer 3

When in doubt, make a diagram.

and decide for yourself the equation for n bounces.