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Mathematics 20 Online
OpenStudy (anonymous):

Can someone please help me with this problem see attachment

OpenStudy (anonymous):

OpenStudy (anonymous):

@ash2326 can you please help me with this problem

OpenStudy (ash2326):

@farmergirl411 Is this a home work question?

OpenStudy (anonymous):

yes

OpenStudy (ash2326):

cool, ok Boat is bobbing up and down with the equation: \[y(t)=40+\sin {3\pi t}\] Do you understand what the equation implies?

OpenStudy (anonymous):

yes

OpenStudy (anonymous):

I understand what it means but how do you find the y'(5)?

OpenStudy (phi):

Ash knows what he's doing.

OpenStudy (anonymous):

ok but oh he is back sorry I thought he left

OpenStudy (anonymous):

@ash2326 what do I do next

OpenStudy (phi):

It would help if you take notes on how you solve these problems. You keep asking how to do problems that are very close to the same problem (or at least use the same ideas)

OpenStudy (anonymous):

are you still there ash can you help me

OpenStudy (anonymous):

ARE U STILL THERE?

OpenStudy (phi):

can you take the derivative with respect to t of \[ y(t)=40+\sin {3\pi t} \]

OpenStudy (anonymous):

yes ans you get 3piecos(3piet)

OpenStudy (phi):

pie is something you eat. pi is a Greek letter. in math, it stands for 3.14159.... you now know \[ y'(t)= 3 \pi \cos(3 \pi t) \] what is y'(5) ?

OpenStudy (anonymous):

That is where I get confused do you just put the 5 where the t is

OpenStudy (phi):

yes, if you have a function f(x) and they ask for f(5), that means replace x with 5 in the definition, and simplify

OpenStudy (anonymous):

right I knew that but when you get the derivative in there that is where I get confused

OpenStudy (anonymous):

=6.4128 correct for final answer

OpenStudy (ash2326):

sorry farmer girl, I had to go out for sometime. Are you through the problem?

OpenStudy (anonymous):

yes thats ok I just didn;t know where you went I got hat for my final answer can you check to just make sure it is ok

OpenStudy (phi):

you should get - 3 pi

OpenStudy (ash2326):

If you put t=5 \[y'(5)=3\pi\cos {15\pi}\] \[\cos{15\pi}=-1\] so \[y'(5)=-3\pi=-9.42\] Do you get it?

OpenStudy (anonymous):

where si you get 15 from

OpenStudy (ash2326):

\[\cos {3\pi}[t\] t=5\[\cos {3\times \pi\times 5}=\cos{15\pi}\]

OpenStudy (anonymous):

ok gotcha and then that number we got means minutes since the boat anchored correct?

OpenStudy (ash2326):

y(t) is the height of boat at time t y'(t) is the speed of boat in vertical direction at time t y'(5) is the speed of boat in vertical direction at time t=5 this is negative which indicates that boat is going down at t=5 Do you get this? @farmergirl411

OpenStudy (anonymous):

yes so the -9.42 means that the boat is going down at t=5

OpenStudy (ash2326):

yes, had it been a positive no. the boat's speed would be positive and the boat would be going up.

OpenStudy (anonymous):

ok gotcha thanks

OpenStudy (ash2326):

yeah :D

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