SOLUTION: I know this is a quadratic equation(word problem)I just can't make it work. This is the last algebra problem I hope to have. If a stone is tossed from the top of a 250 meter bui

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Question 622025: I know this is a quadratic equation(word problem)I just can't make it work. This is the last algebra problem I hope to have.
If a stone is tossed from the top of a 250 meter building, the height of the stone as a function of time is given by h(t)= -9.8t^2 - 10t + 250, where t is in seconds, and height is in meters. After how seconds will the stone hit the ground? Round to the nearest hundreths place.
Thanks so much

Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 

Hi,

by h(t)= -9.8t^2 - 10t + 250, where t is in seconds, and height is in meters. 

Hits the ground, then h =0

  -9.8t^2 - 10t + 250 = 0

t+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+ 

t+=+%2810+%2B-+sqrt%28+9900%29%29%2F%28-19.6%29+ 

throwing out negative solution for time

 t = 4.566sec