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Math Help - Point Of Inflection

  1. #1
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    Point Of Inflection

    Show that for any cubic function of the form y=ax^3+ bx^2 +cx +d, there is a single point of inflection where the slope of the curve at that point is c-(b^2/3a)
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  2. #2
    Super Member 11rdc11's Avatar
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    Can you show us the work you completed so far?
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  3. #3
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    u find second derivative of function
    f"=c-(b^2/3a)? and thn u sovle for wht?
    i dont even know i m rit or wronge
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  4. #4
    Super Member 11rdc11's Avatar
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    once you find the second derivative set it equal to 0 and solve for x
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  5. #5
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    6a+2b=0
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  6. #6
    Super Member 11rdc11's Avatar
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    but solve it for x

    x = \frac{-2b}{6a}

    Now replace x in the first derivative with the x you just solved for in the 2nd derivative and simplify
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  7. #7
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    Quote Originally Posted by ilovemymath View Post
    6a+2b=0
    No, 6ax+ 2b= 0. Solve for x.
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