Question 1205519


{{{H(t)=-16x^2+64x+9}}}   this is a parabola that opens down

 so we can find {{{t}}} coordinate of the maximum using the formula

{{{t=-b/2a}}} where {{{b=64}}} and {{{a=-16}}}

{{{t=-64/(2(-16))}}}

{{{t=-64/(-32)}}}

{{{t=2}}}


answer:

B.{{{2 }}}seconds