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Calculus people!

Discussion in 'The Lounge' started by thezentree, Nov 20, 2006.

  1. thezentree

    thezentree 3/4 ton status

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    What is the first derivative of x^2(x-3)?
     
  2. Resurrection_Joe

    Resurrection_Joe 1 ton status

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  3. WRENCH-HEAD

    WRENCH-HEAD 1/2 ton status

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    3x^2-6x or 3x(x-3)
     
  4. ct85k10

    ct85k10 1/2 ton status

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    3x^2-6x
     
  5. Russell

    Russell LB7 Tahoe Status Premium Member GMOTM Winner

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    Gotta use the multiplication rule for that problem. I was taught it as U`V + UV`, aka, the derivative of the first term, times the second, plus the first term time the derivative of the second. However, since the second term is in brackets, we need to use the chain rule to determine it's derivative.

    That gives us 2x(x-3) + X^2(1)(x-3)^0(1), which can be simplified down to 2x^2 - 3x + x^2, then to 3x^2 - 3x, then further down to x^2 - x.

    We didn't have to use the chain rule in this case, as anything to the power of 0 is 1, but its good practice to do so incase you come across something in brackets to the power of some other number.
     
  6. ct85k10

    ct85k10 1/2 ton status

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    my roomate and i may be wrong but shouldent it be

    That gives us 2x(x-3) + X^2(1)(x-3)^0(1), which can be simplified down to 2x^2 - 6x + x^2, then to 3x^2 - 6x, then further down to x^2 - 2x.

    because 2x(x-3) simplifyes to 2x^2-6x
     
  7. Russell

    Russell LB7 Tahoe Status Premium Member GMOTM Winner

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    Yep, your right!

    I totally missed the 3 x 2 :D
     
  8. UseYourBlinker

    UseYourBlinker 1 ton status

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  9. thezentree

    thezentree 3/4 ton status

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    Apparently I'm not capable of basic algebra. Good thing I'm taking a calculus exam in the morning. :doah:
     
  10. sarasotausmc

    sarasotausmc 1/2 ton status GMOTM Winner

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    Dammit, I came up with 3. Hang on, let me redo that calculation. I'll get right back with ya.
     
  11. Resurrection_Joe

    Resurrection_Joe 1 ton status

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    It's ****ing seven, everything is seven...
     
  12. Homeslice

    Homeslice 1/2 ton status

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    that hurts my brain..
     

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