Monday, February 15, 2010

26

formulas for derivatives

d/dx c=0 (c is a #)
d/dx cu=cu' (c is #)
d/dx cx=c (c is a #)
d/dx u+v=u'+v'
d/dx uv=uv'+vu'
d/dx u/v=(vu'-uv')/v^2
d/dx sinx=cosx(x')
d/dx cosx=-sinx(x')
d/dx tanx=sec^2x(x')
d/dx secx=secxtanx(x')
d/dx cscx=-cscxtanx(x')
d/dx cotx=-csc^2x(x')
d/dx lnu= 1/u(u')
d/dx e^u=e^u(u')

***just remember that integration is opposite for all these derivative formulas. ***

Optimization can be used for finding the maximum/minimum amount of area of something. Steps in order to optimize anything:
1. Identify primary and secondary equations. Primary deals with the variable that is being maximized or minimized. The secondary equation is usually the other equation that ties in all the information given in the problem.
2. Solve the secondary equation for one variable and then plug that variable back into the primary. If the primary equation only have one variable you can skip this step.
3. Take the derivative of the primary equation after plugging in the variable, set it equal to zero, and then solve for the variable.
4. Plug that variable back into the secondary equation in order to solve for the last missing variable. Check endpoint if necessary to find the maximum or minimum answers

Im having a little trouble with intergration of trig functions. I need some help with that.

3 comments:

  1. integration of trig functions is pretty much exact opposite of the derivative of that trig function. for instance, if something is negative, its positive. if it's sin, then it's cos.
    ln integration is very helpful and so is tan inverse integration.
    ln integration is when the top is the derivative of the bottom.

    ReplyDelete
  2. to elaborate a bit more on what sarah was saying...

    when you integrate tan sometimes it's easier to just change it to sin/cos first then you set your u to cosx and du to -sinx. Now you need a negative on outside so the integral is

    - S du/u so now its just -ln|u| which is -ln|cosx|+C.

    ReplyDelete
  3. John and Sarah pretty much explained it all, but don't forget about the identities and the trig-inverse identities!
    They were a bunch of formulas B-Rob gave us a while back...they're probably in your notes

    ReplyDelete