A community for students.

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

anonymous

  • one year ago

I am asked to find the change of A with respect to r, when r=4 the problem reads: A=2700[1+(r/1200)]^96 The available choices are: A) dA/dr= 297.3 B) dA/dr= 216.72 C) dA/dr= 217.44 D) dA/dr= 296.31 I don't understand how to do this even after substituting 4 for the r

  • This Question is Closed
  1. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    what do you get for dA/dr ?

  2. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Use a order of operation. PEMDAS First to do is the paratheis

  3. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    you need to find the derivative of A

  4. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    How do I find a derivative of something with no variable?

  5. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    the variable is r

  6. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    (1.003)^96=96.288 96.288*2700=259977.6

  7. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    yes the variable is r, and r is 4

  8. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    that's not the way to do this you need to find a rate of change so you differentiate

  9. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    You are working out A not dA/dr

  10. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    how would I work our dA/dr?

  11. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    dA / dr = 2700* 96(1 + r/1200)^95 * 1/1200

  12. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    - use the chain rule

  13. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    so plug in r = 4 and you have your answer

  14. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    You'll need a calculator for that , of course

  15. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    259200?

  16. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    No

  17. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    It comes to one of the choices

  18. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    If you have a graphical calculator you can just type it in as above otherwise it might be better to work out the parentheses first then the exponential (^95), then multiply by 2700 , by 96 and then divide by 1200

  19. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Wow, I have no idea how you figured out how to do it like that, but it works. I will be thinking about this one all day. Thanks

  20. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 4

    the derivative dA/dr gives you the rate of change of area with respect to r. by plugging in r = 4 you get the rate of change when r = 4.

  21. Not the answer you are looking for?
    Search for more explanations.

    • Attachments:

Ask your own question

Sign Up
Find more explanations on OpenStudy
Privacy Policy

Your question is ready. Sign up for free to start getting answers.

spraguer (Moderator)
5 → View Detailed Profile

is replying to Can someone tell me what button the professor is hitting...

23

  • Teamwork 19 Teammate
  • Problem Solving 19 Hero
  • You have blocked this person.
  • ✔ You're a fan Checking fan status...

Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.

This is the testimonial you wrote.
You haven't written a testimonial for Owlfred.