8. A record label uses the following function to model the sales of a new release.
A(t) = -90t^2 + 8100t. The number of albums sold is a function of time, t, in days. On which day were the most albums sold?

Question

8. A record label uses the following function to model the sales of a new release. 
A(t) = -90t^2 + 8100t. The number of albums sold is a function of time, t, in days. On which day were the most albums sold?

firejay5 · Answer

Is it Day 45???

anonymous · Answer

so we want the maximum I guess. Take the derivative, setting it equal to 0, and solve for t

anonymous · Answer

Did you take the derivative?

firejay5 · Answer

I type it in http://www.wolframalpha.com/input/?i=8.+A+record+label+uses+the+following+function+to+model+the+sales+of+a+new+release.+A%28t%29+%3D+-90t^2+%2B+8100t.+The+number+of+albums+sold+is+a+function+of+time%2C+t%2C+in+days.+On+which+day+were+the+most+albums

anonymous · Answer

Do you know how to take the derivative? Have you been taught that yet? What class is this for? I should be careful as to how I teach you to solve this

firejay5 · Answer

We haven't been taught derivative yet

anonymous · Answer

ya you wouldn't have been taught that yet. It's so easy that way tho :(

$$A(t) = -90t^2 + 8100t$$$$A'(t) = -180t + 8100$$$$0 = -180t + 8100$$$$180t=8100$$$$t=45$$
That is the calculus way. I almost want to teach you that. hmm...

Algebra 2 method I would graph that on my calculator and use my calculator to find the maximum. Are you allowed to use a graphing calculator for this question?

firejay5 · Answer

Wolframalpha helped me out and was it right

anonymous · Answer

ya it's right.

firejay5 · Answer

wow! I have 1 more word problem and I will try and figure it out and if not I'll have you help me on it okay

anonymous · Answer

sure

firejay5 · Answer

thanks