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Math Help - a consecutive number question

  1. #1
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    a consecutive number question

    <br /> <br />
11+13+15..........+(2n-1)=n^2 - x^2<br />

    x=?

    A) 3
    B) 4
    C) 5
    D) 6
    E) 7
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  2. #2
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    Quote Originally Posted by OPETH View Post
    <br /> <br />
11+13+15..........+(2n-1)=n^2 - x^2<br />

    x=?

    A) 3
    B) 4
    C) 5
    D) 6
    E) 7
    Can you find the value of the left hand side by using the formula for the sum of an arithmetic series ......? a = 11, d = 2, number of terms = n - 5.

    Then equate the value of the left hand side to n^2 - x^2 and solve for x.
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