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Math Help - ratio test, i need a bit of clarification

  1. #1
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    ratio test, i need a bit of clarification

    i'm looking at this problem online, and i don't understand how they came up with the answer.
    Visual Calculus - Series - 12

    so when they add 1, how does (2n-1) turn into (2n+1)? wouldn't the -1 and +1 cancel out, and it'd just be 2n?
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by isuckatcalc View Post
    i'm looking at this problem online, and i don't understand how they came up with the answer.
    Visual Calculus - Series - 12

    so when they add 1, how does (2n-1) turn into (2n+1)? wouldn't the -1 and +1 cancel out, and it'd just be 2n?
    no, you replace n with (n + 1), so 2n - 1 ---> 2(n + 1) - 1 = 2n + 2 - 1 = 2n + 1

    note that things should be in absolute values
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  3. #3
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    Which problem in that exercise are you referring to?
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  4. #4
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    sorry, i thought i linked directly to it. i meant the third one down the list.

    thanks jhevon, that makes much more sense.
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