The function f(t)=-3t^212t15 models the approxiamte height of n object t seconds after it is launched. How many seconds does it take the object to hit the ground

Question

Math problems about quadratics & geometry

a. 3 seconds

b. 4 seconds

c. 5 seconds

d. 6 seconds

Answer 1

I assume your quadratic equation is -3t² + 12t + 15.

Since the height will be zero when it hits the ground, solve the following equation:

-3t² + 12t + 15 = 0

Divide both sides by -3.

t² - 4t - 5 = 0 Factor.

(t - 5)(t + 1) = 0

t - 5 = 0 or t + 1 = 0

t = 5 seconds t = -1, illogical answer