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Math Help - Differentiation Help

  1. #1
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    Differentiation Help

    I've been working on this problem and can't figure out how to get to the right answer.

    The problem:
    (5x-2)^2(2-x^4)^4

    I got:
    2(5x-2)(2-x^4)^3(20+16x^3-50x^4)
    But the correct answer, according to the online set, is:
    2(5x-2)(2-x^4)^3(10+16x^3-45x^4)

    I sometimes get tripped up on factoring out, but I can't see where I went wrong. My answer seems right. I don't know how to get to the correct answer.
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  2. #2
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    Re: Differentiation Help

    Quote Originally Posted by crumiecake View Post
    I've been working on this problem and can't figure out how to get to the right answer.

    The problem:
    (5x-2)^2(2-x^4)^4

    I got:
    2(5x-2)(2-x^4)^3(20+16x^3-50x^4)
    But the correct answer, according to the online set, is:
    2(5x-2)(2-x^4)^3(10+16x^3-45x^4)

    I sometimes get tripped up on factoring out, but I can't see where I went wrong. My answer seems right. I don't know how to get to the correct answer.
    next time, show your steps so that one may possibly locate your error ...

    (5x-2)^2 \cdot 4(2-x^4)^3 \cdot (-4x^3) + (2-x^4)^4 \cdot 2(5x-2) \cdot 5

    2(5x-2)(2-x^4)^3 [(5x-2)(-8x^3) + 5(2-x^4)]

    2(5x-2)(2-x^4)^3 [-40x^4 + 16x^3 + 10 - 5x^4]

    2(5x-2)(2-x^4)^3 (-45x^4 + 16x^3 + 10)
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