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HELP! Derivative problems, involving the quotient rule and trig!?

The question is:

Given f(x) = 2x/sin3x, find f' of (pi/3).

My work is as follows:

f'(x) = ((sin3x)(2) - 2x(3cos3x))/(sin3x)2

However, this isn't right! Where did I go wrong? And the denominator is equal to zero! How does this work?

Update:

The question is:

Given f(x) = 2x/sin3x, find f' of (pi/3).

My work is as follows:

f'(x) = ((sin3x)(2) - 2x(3cos3x))/(sin3x)^2

However, this isn't right! Where did I go wrong? And the denominator is equal to zero! How does this work?

3 Answers

Relevance
  • 1 decade ago
    Favorite Answer

    think you are close but,

    your first term should be 2/sin3x,

    just the d/dx(2x)/sin3x

    I think you've got then the second term right but just left of the power

    f'(x) = 2/(sin3x) - 2x(3cos3x)/(sin3x)^2

  • 1 decade ago

    I just learned this, you don't go to Elder do you?

    would it would be f'= ((sin3x)(2)- (2x)(cos3))/(sin3x)2

  • Anonymous
    4 years ago

    for this issue you wouldnt favor chain rule. you take advantage of chain rule once you've a function interior of a function. so as an example, sin(x^2 + a million). you wanna artwork outdoors to interior so that you may want to first commence with the sin element. by-product of sin is cos. so that you may want to get cos(x^2 + a million). now flow on to the interior. the by-product of x^2 + a million is an similar as 2x. so now multiply those mutually and also you get 2xcos(x^2 + a million). thats your answer.

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