Assignment:
Question 1. Luigi launches a stone vertically upward from the top of a cliff. The height of the stone above the base of the cliff is appoximated by the model h=65+10t-5t^2 , where t is time in second and h is height in metres
a) How high is the stone above the base of the cliff after 3 seconds?
h = 65 + 10t - 5t^2
h = 65 +10(3) - 5(3)^2
h = 65 +30 - 45
h = 50 m
b) How long does it take for the stone to reach 50m above the base of the cliff?
h = 65 + 10t - 5t^2
h = 65 + 10t - 5t^2
-65 + 50 = 10t - 5t^2
-15 = 10t - 5t^2
can someone help me from here?
c) How long does it take for the stone to hit the ground at the base of the cliff?