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Do I have to expand when I use the chain rule? watch

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    Let's say I have to different y=3(4-x)^8

    Is the answer 24(4-x)^7(-1)

    Or do I have to expand this? Is this even correct?
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    expand?
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    (Original post by TeeEm)
    expand?
    the brackets?

    So instead of 24(4-x)^7(-1)

    I get (-96+24x)^7
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    your method is fine. you can join up the 24 and the -1, but leave the rest in brackets ?
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    (Original post by Dinasaurus)
    the brackets?

    So instead of 24(4-x)^7(-1)

    I get (-96+24x)^7
    that is incorrect !!
    the bracket is "locked" to the power of 7
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    (Original post by TeeEm)
    that is incorrect !!
    the bracket is "locked" to the power of 7
    So was it correct the first time round? Is it normal for chain rule answers to be so messy?
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    (Original post by Dinasaurus)
    the brackets?

    So instead of 24(4-x)^7(-1)

    I get (-96+24x)^7
    (-96+24x)^7 is not the same as 24(4-x)^7(-1), you'd have to use the binomial expansion to expand the (4-x)^7 term. With these questions, it's always best to just leave it as it is, except multiply the (-1) and (24) together. It's correct, by the way :P
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    (Original post by Dinasaurus)
    So was it correct the first time round? Is it normal for chain rule answers to be so messy?
    it was fine.

    (they are not messy)
 
 
 
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