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    Have I done this series expansion correctly, if so how do I get to the final answer from there as I'm not sure what else I have to do
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    (Original post by Samii123)

    Have I done this series expansion correctly, if so how do I get to the final answer from there as I'm not sure what else I have to do
    Your final term should be -\dfrac{1}{512}x^3. Note the minus sign. Rest are OK, although:

    Problem comes from your powers of "x". They should be \left(-\dfrac{1}{4}x\right)^n. Again the minus sign.

    To find \sqrt{3.9999} what value must x take so that 4-x = 3.9999, and sub into your expansion.
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    (Original post by ghostwalker)
    Your final term should be -\dfrac{1}{512}x^3. Note the minus sign. Rest are OK, although:

    Problem comes from your powers of "x". They should be \left(-\dfrac{1}{4}x\right)^n. Again the minus sign.

    To find \sqrt{3.9999} what value must x take so that 4-x = 3.9999, and sub into your expansion.
    Ahhhhh ok thank you for the help!
 
 
 
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