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anonymous
 one year ago
Find f if f''(x)=2e^t+3sin(t), f(0)=7, f(pi)=8
anonymous
 one year ago
Find f if f''(x)=2e^t+3sin(t), f(0)=7, f(pi)=8

This Question is Closed

FireKat97
 one year ago
Best ResponseYou've already chosen the best response.3because you have been given f"(x) you need to integrate twice to get to f'(x) and then f(x)

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I have been doing that but have not gotten the correct response

FireKat97
 one year ago
Best ResponseYou've already chosen the best response.3Can you post your working so far?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I have quite a few different problems But I only have one more chance to get it right.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Like I have worked them a lot

FireKat97
 one year ago
Best ResponseYou've already chosen the best response.3but can you show me how you went about trying to solve the problem? So your working out so I can see where you're going wrong..

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I am not exactly sure how to take a photo and attach a file since I am on my computer.

FireKat97
 one year ago
Best ResponseYou've already chosen the best response.3do you think you could type up your solution?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0its a kinda complicated solution thats why i am on here trying to get an answer for it so i an compare the correct answer to my answer to see where i went wrong

FireKat97
 one year ago
Best ResponseYou've already chosen the best response.3okay so when you integrate 2e^x what do you get?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.02e^x anything e^x is still e^x

FireKat97
 one year ago
Best ResponseYou've already chosen the best response.3sorry what do you get when you integrate 3sint

FireKat97
 one year ago
Best ResponseYou've already chosen the best response.3Yup, thats correct too, so we know that the integral of f"(x) is 2e^t  3cost + c

FireKat97
 one year ago
Best ResponseYou've already chosen the best response.3so f'(x) = 2e^t  3cost so now we have to integrate again

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I am running out of time its an online homework due at a specific time Can you tell me the answer? I only have one last attempt and 2/23 problems left that I have been struggling with for the past hour and a half

FireKat97
 one year ago
Best ResponseYou've already chosen the best response.3you're not going to learn if i just tell you the answer..

FireKat97
 one year ago
Best ResponseYou've already chosen the best response.3just try integrating f'(x) = 2e^t  3cost + c in the same way and tell me what you get

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0The tricky part with this question is that you have two constants since you have to integrate twice I understand the mechanics of how to do the problem and with you not telling me your answer I can't know if it is correct so if the answer you have is wrong then I am learning the wrong thing I have tried 4 different answers so if you tell me your answer I can check to see if that was one of the answers I got

freckles
 one year ago
Best ResponseYou've already chosen the best response.2he and you are both correct and saying f'(x)=2e^t3cos(t)+c you can integrate first... or you can use your constraint to find c...wait isn't one of your constraints written incorrectly...one of them should be f'(a)=b where a and b are some numbers ...whichever one it is use the constraint then integrate note: if you integrate first make sure you don't use the same letter for the other constant you get after the next integration

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0But what is the final answer that you get ?

freckles
 one year ago
Best ResponseYou've already chosen the best response.2No one can know the problem is incorrectly stated

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0What do you mean it is incorrectly stated ?

freckles
 one year ago
Best ResponseYou've already chosen the best response.2As I was saying earlier isn't one of your constraints is suppose to be in the form f'(a)=b where and b are some numbers?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0yes it is supposed to be but the two questions I was stuck on do not give it in the form of f(x) and f'(x) which is why it is difficult But it can be done I know the steps but keep getting the wrong answer

freckles
 one year ago
Best ResponseYou've already chosen the best response.2where a and b are some numbers*

FireKat97
 one year ago
Best ResponseYou've already chosen the best response.3No, not necessarily.

freckles
 one year ago
Best ResponseYou've already chosen the best response.2err... do you not have a condition on f'?

FireKat97
 one year ago
Best ResponseYou've already chosen the best response.3In this case, because f(0) is given, cx can be eliminated giving the constant d

freckles
 one year ago
Best ResponseYou've already chosen the best response.2you have f(0)=7 and f(pi)=8 one of these is really suppose to be about f'

FireKat97
 one year ago
Best ResponseYou've already chosen the best response.3what I mean is f(x) = 2e^t  3sint + cx + d we can find d and hence when we sub in f(pi) = 8, the value of d is already known so we can find c as well

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0no you are supposed to integrate twice fine the constant of the first integrated equation integrate again and then solve for the second constant and plug everything back into the integrated problem that gave the equation for f(x)

FireKat97
 one year ago
Best ResponseYou've already chosen the best response.3because since f(0) = 7 is known, everything except d is equal to 0, so d = 7

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0FireKat97 that is what I have been doing and keep getting the wrong answer Can you tell me your answer so that I can see if it is correct and then send me a picture of your work ?

FireKat97
 one year ago
Best ResponseYou've already chosen the best response.3then we know that f(pi) = 8 = 2e^π  3sinπ + cπ + 7 and c can now be found too

FireKat97
 one year ago
Best ResponseYou've already chosen the best response.3I got f(x) = 2e^t  3sin(t) + t(15  2e^t)/π + 7 hoping I didn't make any silly mistakes along the way...

freckles
 one year ago
Best ResponseYou've already chosen the best response.2I guess you guys were right about f(0)=7 and f(pi)=8 I was just thinking they normally give a condition for each integration step but I got a different d and c above using the conditions

FireKat97
 one year ago
Best ResponseYou've already chosen the best response.3Unless f(0) is given, something about f'(x) is required

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0the answer you gave was incorrect FireKat97

FireKat97
 one year ago
Best ResponseYou've already chosen the best response.3do they need it in decimals if its an online quiz thing

freckles
 one year ago
Best ResponseYou've already chosen the best response.2but yeah f(0)=7 doesn't give d=7 you should get 23(0)+c(0)+d=7 which this will give us a different c in the end also

FireKat97
 one year ago
Best ResponseYou've already chosen the best response.3OH wait whoops! yeah

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0so wait what should the answer be ?

FireKat97
 one year ago
Best ResponseYou've already chosen the best response.3because e^0 = 1 not 0

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0so instead of 7 it should be 5 ?

FireKat97
 one year ago
Best ResponseYou've already chosen the best response.3yeah and so when you sub d in again for f(pi) = 8, use d as 5, so c should be different too

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0okay i give up I just won't get points for this problem lol

FireKat97
 one year ago
Best ResponseYou've already chosen the best response.3don't give up, you're almost there :p

zepdrix
 one year ago
Best ResponseYou've already chosen the best response.0broski, ask for help on a question sooner than 30 minutes before the due date! XD that's crazy sauce!

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I still don't have an answer lol so I do not feel almost there

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I have more than 30 minutes..

zepdrix
 one year ago
Best ResponseYou've already chosen the best response.0For future reference, when you get into a jam like this, https://www.wolframalpha.com/input/?i=f%27%27%28t%29%3D2e%5Et%2B3sin%28t%29%2C+f%280%29%3D7%2C+f%28pi%29%3D8 Wolfram is really helpful with problems such as this one. Unless your teacher considers that cheating of course :p I find it to be a useful tool to check work though.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I have already tried wolfram and it does not work either not for this problem

FireKat97
 one year ago
Best ResponseYou've already chosen the best response.3i copied and pasted and forgot to get fix the 5 :p haha

zepdrix
 one year ago
Best ResponseYou've already chosen the best response.0inputting into wolfram is a little tricky :O I think I did it correctly though, didn't i?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0so that is not the correct answer FIREKAT?

freckles
 one year ago
Best ResponseYou've already chosen the best response.2@Asiah321 we said d=5 and you had f(t)= 2e^t  3sint + cx + 5 so now use this other condition f(pi) = 8 plug in pi for t and replace f(pi) wth 8 and solve for c

freckles
 one year ago
Best ResponseYou've already chosen the best response.2oops that x should be t but whatever

freckles
 one year ago
Best ResponseYou've already chosen the best response.2solve for c: 8=2e^pi3sin(pi)+c(pi)+5

Jhannybean
 one year ago
Best ResponseYou've already chosen the best response.1\[f''(x)=2e^t+3\sin(t)\]\[f'(x)=\int (2e^t+3\sin(t))dt = 2e^t3\cos(t)+c\]\[f(x) = \int (2e^t3\cos(t)+C)dt = 2e^t3\sin(t) +Cx+D\]\[7=2e^{0}3\sin(0)+C(0)+D \implies D = 5\]\[8 = 2e^{\pi} 3\sin(\pi)+\pi C+5\]\[\pi C = 2e^{\pi}13 \qquad \implies C=\frac{2e^{\pi}13}{\pi}\]\[f(x) = ....\]

Jhannybean
 one year ago
Best ResponseYou've already chosen the best response.1Therefore, what im getting for \(f(x)\) is.. \[f(x) = 2e^{t}3\sin(t)+\left(\frac{2e^{\pi}13}{\pi}\right)t+5\]

Jhannybean
 one year ago
Best ResponseYou've already chosen the best response.1some variable errors. But you can figure out that much

freckles
 one year ago
Best ResponseYou've already chosen the best response.2lol is it f(x) or f(t)

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Jhannybean it was correct !!!! thank you so muchhhhh !!!!

Jhannybean
 one year ago
Best ResponseYou've already chosen the best response.1Whatever, it's f(o)

freckles
 one year ago
Best ResponseYou've already chosen the best response.2I only wanted to point that out because there has been a bunch of mixing of variables in this post

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0jhannybean can you check your messages please

Jhannybean
 one year ago
Best ResponseYou've already chosen the best response.1Yeah, that's why i just went with what I thought it was.

Jhannybean
 one year ago
Best ResponseYou've already chosen the best response.1You shouldn't be thanking me, honestly. I was working it out while @freckles and @FireKat97 we're helping you solve it:P Sometimes you have to work with people instead of asking fr the answer.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I really appreciate you all ! I have been struggling with this problem and another one for a while

Jhannybean
 one year ago
Best ResponseYou've already chosen the best response.1post your new question in a new thread :)
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