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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
    y1=1+x
    y2=a^x
    y2'=a^xln(a)
    y1'=1


    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

    Dick

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    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 :)
     
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