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Mathematics 11 Online
OpenStudy (mathmusician):

Some help with calculus optimization please!!

OpenStudy (mathmusician):

I have done problems 1-7.

OpenStudy (mathmusician):

OpenStudy (mathmusician):

@agent0smith

OpenStudy (mathmusician):

I can do number 8 on my own

OpenStudy (mathmusician):

Can someone help with number 9?

OpenStudy (mathmusician):

Okay the formula is \[A(t)=Ce ^{k \sqrt{t}+r(40-t)}\]

OpenStudy (mathmusician):

and the domain is 0≤t≤41

OpenStudy (agent0smith):

Just find the derivative, same as last time. It's not much different, save for r and k.

OpenStudy (mathmusician):

yeah my bad typo

OpenStudy (mathmusician):

\[A'(t)=Ce ^{k \sqrt{t}+r(40-t)}(\frac{ k }{ 2\sqrt{t} }-r)\]

OpenStudy (mathmusician):

Do i find the maximum value now?

OpenStudy (agent0smith):

Yep, same way as last time.

OpenStudy (mathmusician):

Set it equal to zero right?

OpenStudy (agent0smith):

Yep

OpenStudy (mathmusician):

\[t=\frac{ k }{ \sqrt{2}*r }\]

OpenStudy (mathmusician):

is that right?

OpenStudy (agent0smith):

Doesn't look right... solve \[\large \frac{ k }{ 2\sqrt{t} }-r=0\]

OpenStudy (mathmusician):

\[r=\frac{ k }{ \sqrt{2}t }\]

OpenStudy (mathmusician):

whoops

OpenStudy (mathmusician):

√t*2

OpenStudy (agent0smith):

You're solving for t.

OpenStudy (mathmusician):

okay

OpenStudy (agent0smith):

Idk how you forgot that lol. It's the same steps as last time.

OpenStudy (mathmusician):

\[t=\frac{ k ^{2} }{ 4r ^{2} }\]

OpenStudy (mathmusician):

is this right @agent0smith

OpenStudy (agent0smith):

Looks right

OpenStudy (mathmusician):

okay cool so is this topt?

OpenStudy (agent0smith):

Yep

OpenStudy (mathmusician):

Okay cool thanks mate!!

OpenStudy (mathmusician):

@agent0smith for # 10 do i just put in random values or do you think there is certain values that they might be looking for, to prove that my topt equation is right

OpenStudy (agent0smith):

Random values, and you could check your graphs maximum lines up with the t value you found above (you already know it will)

OpenStudy (mathmusician):

okay thanks

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