蓝皮书60题

grassgreen

60. 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

哪位好心人帮我讲讲这道题， 正确答案为什么是B

grassgreen

非常感谢！

davidsfo

由条件知道t=3时h有最大值，所以2秒后，就是t=5，代入式子，得h=86