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Math Help - tangent and secant

  1. #1
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    tangent and secant

    Let f(x)=3^x-x^3. The tangent to the curve is parallel to the secant through (0,1) and (3,0) for x ~?

    how do you go about to solve this?
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  2. #2
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    Quote Originally Posted by got_jane View Post
    Let f(x)=3^x-x^3. The tangent to the curve is parallel to the secant through (0,1) and (3,0) for x ~?

    how do you go about to solve this?
    The gradient of the line passing through (0,1) and (3,0) is 1/3. So solve f'(x) = 1/3 for x. Exact solutions are probably not possible .....
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    Quote Originally Posted by mr fantastic View Post
    The gradient of the line passing through (0,1) and (3,0) is 1/3. So solve f'(x) = 1/3 for x. Exact solutions are probably not possible .....
    so what can I do to approximate?
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  4. #4
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    Quote Originally Posted by got_jane View Post
    so what can I do to approximate?
    You use whatever technology you have access to (graphics calculator, CAS calculator, software such as mathematica, derive etc.) in the appropriate way.
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