Question 116335
{{{a(t) = -90t^2 + 8100t}}}
when is this a maximum?
The vaue od {{{t}}} at maximum is {{{(-b) / (2a)}}}
where {{{a = -90}}}
and {{{b = 8100}}}
{{{(-b) / (2a) = -8100 / 2*(-90)}}}
{{{-8100 / -180 = 45}}}
The max number of albums is sold on day 45
{{{a(t) = -90t^2 + 8100t}}}
{{{a(t) = -90*(45)^2 + 8100*45}}}
{{{a(t) = -182250 + 364500}}}
{{{a(t) = 182250}}} albums sold on day 45