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P1 - Algebra Q watch

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    Stuck on this Q.... If anyone can be bothered enough, plz help! I don't like proof questions.

    E=(x-3y)^2 - x(x-6y) + 2
    a) Prove that E is independent of x.
    b) Find the least value of E and the value of y for which this occurs.
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    (Original post by Mikan18)
    Stuck on this Q.... If anyone can be bothered enough, plz help! I don't like proof questions.

    E=(x-3y)^2 - x(x-6y) + 2
    a) Prove that E is independent of x.
    b) Find the least value of E and the value of y for which this occurs.
    a Expand it so its x62 - 6xy + 9y^2 - x^2 + 6xy + 2 so all the xs cancel, That proves that e is independent of x

    bjust differentiate and put it equals to 0, and the minimum value is the least yalye of e. if you know the value of e you can in turns find why by putting it in the original equation
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    (Original post by Mikan18)
    Stuck on this Q.... If anyone can be bothered enough, plz help! I don't like proof questions.

    E=(x-3y)^2 - x(x-6y) + 2
    a) Prove that E is independent of x.
    b) Find the least value of E and the value of y for which this occurs.
    For (a) expand out the brackets and as E independant of x, there should be no x left in the formula, therefore showing that E is independent of x
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    Did this a few days ago

    http://www.rdoh.com/upload/uploads/6a.jpg
    http://www.rdoh.com/upload/uploads/6b.jpg
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    Thanks a lot all.
 
 
 
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