SOLUTION: how many terms of the series 4+6+8+10... add to 180

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Question 880991: how many terms of the series 4+6+8+10... add to 180
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
General term, 4%2B%28n-1%29%2A2.
Series, %28n%2F2%29%284%2B4%2B%28n-1%29%2A2%29=180, and you can either derive the formula or refer to any suitable reference source.
%28n%2F2%29%288%2B2n-2%29=180
n%286%2B2n%29=360
2n%5E2%2B6n-360=0
highlight_green%28n%5E2%2B3n-180=0%29
highlight%28%28n-12%29%28n%2B15%29=0%29
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TWELVE TERMS.