SOLUTION: The Empire State Bldg is 1250 ft tall. If an object thrown upward from the top of the building at an initial velocity of 35 ft per second, its height after "t" seconds after it is

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons -> SOLUTION: The Empire State Bldg is 1250 ft tall. If an object thrown upward from the top of the building at an initial velocity of 35 ft per second, its height after "t" seconds after it is       Log On


   

Question 32495: The Empire State Bldg is 1250 ft tall. If an object thrown upward from the top of the building at an initial velocity of 35 ft per second, its height after "t" seconds after it is thrown is given by the
function h(t)= -16t^2+35t+1250. How long will it be before the oject hits the ground?
Answer by Fermat(136) About Me  (Show Source):
You can put this solution on YOUR website!
h(t)= -16t^2+35t+1250
you have to find the time when h = 0 - that's when it hits the ground.
-16t^2+35t+1250 = 0
16tē - 35 - 1250 = 0
using the quadratic formula, t+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+, we get
t+=+%2835+%2B-+sqrt%28+%28-35%29%5E2-4%2A%2816%29%2A%28-1250%29+%29%29%2F%282%2A16%29+
t+=+%2835+%2B-+sqrt%28+1225+%2B+80000%29+%29%2F%2832%29+
t+=+%2835+%2B-+285+%29%2F32+
t+=+320%2F32, t+=+-250%2F32+
t=10, t=-7.8125
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