10 plays
Divide 2/5 and 4 by 2 to get 1/5 and 2
For every 1/5 of practice he teaches the ten 2 plays
5/5 = 1
So 5*2 = 10 plays
The rock will hit the ground when y=0, so we need to solve this equation for its roots. To do that, we set it equal to 0:
Divide everything by -0.005 to clear out the decimals:
Now use the quadratic formula:
or
We want the larger x value since the smaller one is when the rock will reach the top of the hole.
Answer:
YES
The following is a function.