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: Find values of A for two functions tangent at a point

  1. Sep 22, 2012 #1
    1. The problem statement, all variables and given/known data
    For what values of a are y=a^x and y=1+x tangent at x=0? Explain

    2. Relevant equations

    3. The attempt at a solution
    Since both equations are tangent at x=0 i set their derivatives equal to each other in hopes of getting a a^xln(a)=1 I then substitute x in that equation with 0 and end up with ln(a)=1.
    I end up with a = e. Is this correct?
  2. jcsd
  3. Sep 22, 2012 #2


    User Avatar
    Science Advisor
    Homework Helper

    It sure is correct. You also checked that y1(0)=y2(0), yes?
  4. Sep 22, 2012 #3
    No i did not, but in hindsight i should have done that. Thanks for the reminder :)
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook