GWD-26-Q21

nicboy

    

Q21:

    

An object thrown directly upward is at a height of h
feet after t seconds, where h = -16 (t - 3)²  + 150. 
At what height, in feet, is the object 2 seconds after it reaches its
maximum height?

    

 

    

A.  
6

    

B. 86

    

C. 134

    

D
             150

    

E.  214

    

                                                                              Answer:
 B

是怎样得到B的啊，谢谢

[此贴子已经被作者于2008-7-3 16:14:56编辑过]

xuhanbing217

根据，抛物线的性质，当T=3时达最高点，2分钟后就是T=5，带进去算就是啦。