A dolphin jumps out of the water and tries to hit a red ball which is 1.5 m above the
water level. After t seconds, the height ( h m) of the dolphin above the water level is given by h = ( 12/5 ) t - t^2
When will the dolphin reach its maximum height?
Ans: 1.2s
F4 Maths @@
2009-11-22 11:30 pm
回答 (1)
2009-11-23 12:29 am
✔ 最佳答案
h= (12/5)t - t^2
= - (t^2 - (12/5)t)
= - (t^2 - 2(6/5)t + (6/5)^2 - (6/5)^2 )
= - (t^2 - 2(6/5)t + (6/5)^2) + (6/5)^2
= - (t - 6/5)^2 + (6/5)^2
when t = 6/5 ,
h have the maximum value.
So t seconds = 6/5 = 1.2 seconds the dolphin reach its maximum height.
收錄日期: 2021-04-21 22:05:19
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