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? asked in Science & MathematicsMathematics · 10 years ago

f(x) = [5 \sqrt(x)] x [(x^3- (2 \sqrt(x) +2 ), find f'( x )?

derivatives. I don't even know which rule to use. I used the product rule and got 15x-6x^(-1/4)+5x^(-1/2)+2.5^(-3/2) but I'm wrong... anyone know it... after the formula I need to find f ' (x)=3 but the equation for the tangent is what I need....

Update:

I ma so confused..at this point I can't even remember the algebra that goes into it... I can't even remember if I can take 5 sqrt2 and muttiply it times 3x^2 and get 15x... is that even right? I had a 5 year gap between algebra and calc. I'm lost

2 Answers

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  • Anonymous
    10 years ago
    Favorite Answer

    f(x) = 5√x * (x³ - 2√x - 2)

    Use the product rule...

    d/dx [fg] = f'g + fg'

    We let...

    f = 5√x = 5x^(½)

    f' = 5/(2x^(½))

    g = x³ - 2x^(½) - 2

    g' = 3x² - 1/√(x)

    So we have..

    f'(x) = (5/(2√x))(x³ - 2x^(½) - 2) + 5√x * (3x² - 1/√x)

    I hope this helps!

    Source(s): Knowledge
  • Anonymous
    10 years ago

    for this one you need to use the product rule and then the quotient rule.

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