1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Please check work on derivatives lab

  1. Feb 25, 2010 #1
    1. The problem statement, all variables and given/known data
    Sorry about not using the template, but I didn't really see how I could have. If you guys/gals could please check over my answers to these questions and point out the ones I miss that would be outstanding. Thank you!!

    1. The position of an object moving on a coordinate line is given by s=t2 −7t+10, were s is in meters
    and t is in seconds. When, if ever, during the interval 0≤ t ≤7 does the object change directions?
    Answer: at t = 3.5 sec

    2. At time t, the position of an object moving along the s axis is s=t3−15t2+78t were s is in meters
    and t is in seconds. Find the total distance traveled by the object from t = 0 to t = 3 .
    Answer: 126 m

    3. Suppose that the cost of producing x radios is given by C(x)=800+40x−0.2x2 . Find the cost per radio of producing the first 30 radios.
    Answer: $60.67

    4. Find the line tangent to the graph of f (x) =cosx at x = pi/2 .
    Answer: y =1

    5. Find the 34th derivative of f (x) = cosx.
    Answer: f 34(x) = −cosx

    6. g(x)=(cscx+cotx)(cscx−cotx) , find g'(x) .
    C. g'(x) = − csc2x <-----not sure about this one.

    7. f (x)= sqrt(11x−x5) , find f '(x) .
    Answer: 1 - (2sqrt(11x-x5))

    8. g(x)=sec5(x2−2x), find g'(x) .
    Answer: 5⋅sec4(x2−2x)tan (x2−2x) <----Really not sure about this one

    9. Find the equation of the line tangent to the graph of f(x) = x3 x3+3 at x =1.
    Answer: y=27/4x-13/4

    10. The total revenue from the sale of x stereos is given by
    R(x) = 2000(1 - x/600)2. Find the marginal
    revenue, if necessary round to the nearest thousandth.
    Answer: R'(x)= 4000(1 - x/600)
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Feb 25, 2010 #2
    I didn't check all of them, 1 is right, 2 I believe is right, I think 4 is -1, 5 is right, 7 is wrong, the answer should be [tex] \frac{11-5x^4}{2\sqrt[2]{(11x-x^5)}$} [/tex].

    You should use http://www.wolframalpha.com/" [Broken] to check your answers, just type in dervive "your equation" and it will show you the answer and steps.
    Last edited by a moderator: May 4, 2017
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook