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Differentiation of natural log

  • 11-05-2009 10:30am
    #1
    getting worse
    Registered Users, Registered Users 2 Posts: 111 ✭✭


    I should know this but it is drving me mad
    If F(x) = Ln 3X2(squared)

    What is the derivative
    a) 2/3X2 (squared) or
    b) 6/3X2 (squared)

    I feel that the answer is b) but doesn't the 3 just shift the curve rather than effecting the slope.

    Thanks for you help


Comments

  • #2
    djpbarry
    Registered Users, Registered Users 2 Posts: 13,104 ✭✭✭✭djpbarry


    getting worse wrote: »
    If F(x) = Ln 3X2(squared)

    What is the derivative
    So f(x) = ln(3x^2) ?

    If so, then f’(x) = (1/3x^2)(6x) = 2x^(-2) (Your answer 'b')


  • #3
    getting worse
    Registered Users, Registered Users 2 Posts: 111 ✭✭getting worse


    thanks for the reply but i think both my answers were wrong

    should the answer not be just 2/X

    as it 6 X . 1/3X^2 = 2/X or 2 X^-1


  • #4
    djpbarry
    Registered Users, Registered Users 2 Posts: 13,104 ✭✭✭✭djpbarry


    getting worse wrote: »
    thanks for the reply but i think both my answers were wrong

    should the answer not be just 2/X

    as it 6 X . 1/3X^2 = 2/X or 2 X^-1
    Yes, that's correct - I just spotted my typo :o.


  • #5
    getting worse
    Registered Users, Registered Users 2 Posts: 111 ✭✭getting worse


    cheers djbbarry
    thanks for your help


This discussion has been closed.
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