When does Kerri enter the pool?

Question

Use the equation h(t)=-3t² -7t + 20

Answer 1

You haven't told the whole story. I am assuming that she is diving from a springboard which lies 20 (feet?) over the water. Is t in seconds?

 

To answer, solve h(t) = 0:

 

-3t² - 7t + 20 = 0.

 

3t² + 7t - 20 = 0  (multiply both sides by -1)

 

(3t - 5)(t + 4) = 0  (factor)

 

3t - 5 = 0  OR  t + 4 = 0   (use the zero product property)

 

y = 5/3 = 1.6 sec or t = -4 sec.

 

The second answer does not make any sense here, so the correct answer would be 1.6 seconds.