Question 30016: The equation (((h=-16^2-32t+320))), gives the height of a ball, thrown downward from the top of a 320ft building with an initial velocity of 32ft/sec. Find the time it takes for the ball to reach a height 160ft. Heres what I have so far, h=160, 160=16t^2+32t+320,160=0,16t^2+32t-320=0,divide by 16,
leaving t^2+2t-20, using the quadratic formula t=b(+or-)radical sign (-2)^2-4(1)(20)/2=0, 2(+or-)radical sign 4+80/2, so the answer I get is 2+ radical sign,84/2, and 2- radical sign 84/2. My math book says the answer is 2.317seconds, but does not show how to get there. Thanks,
Answer by Cintchr(481)   (Show Source):
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