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What is the sum of the arithmetic sequence 137, 125, 113 …, if there are 38 terms?
 one year ago
 one year ago
What is the sum of the arithmetic sequence 137, 125, 113 …, if there are 38 terms?
 one year ago
 one year ago

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myininayaBest ResponseYou've already chosen the best response.2
Do you see that the numbers are increasing by 8?
 one year ago

mariomintchevBest ResponseYou've already chosen the best response.0
i would do it the old school way and keep subtracting 12 until you get 38 terms, then add lol
 one year ago

myininayaBest ResponseYou've already chosen the best response.2
\[\sum_{i=0}^{37}(137+8i)=137+8(0)+\sum_{i=1}^{37}(137+8i)\] Now use \[\sum_{i=1}^{n}i=\frac{n(n+1)}{2} \text{ and } \sum_{i=1}^{n}c=cn\]
 one year ago

NatalieLoveBest ResponseYou've already chosen the best response.0
Im still not getting the correct answer
 one year ago

ZarkonBest ResponseYou've already chosen the best response.0
whay are people using d=8
 one year ago

NatalieLoveBest ResponseYou've already chosen the best response.0
i dont know im gonna guess
 one year ago

FoolForMathBest ResponseYou've already chosen the best response.3
Whenever you need to find the sum of an arithmetic series use this formula: \[ \frac n 2 \left( 2a+ (n1) \right)\times d) \tag{1}\] a= first term n= number of terms d= common difference Here, \(n= 38, a = 137 \) and \( d = 12\). Substituting these in \((1)\), and assuming my algebra is right you answer should be \(3230 \)
 one year ago

NatalieLoveBest ResponseYou've already chosen the best response.0
I know but the answer does not show up in the multiple choose
 one year ago

FoolForMathBest ResponseYou've already chosen the best response.3
@NatalieLove: Revert if you need help in proving that formula.
 one year ago

NatalieLoveBest ResponseYou've already chosen the best response.0
We are doing the same steps the test its incorrect. It does not show up as a choose Thank You
 one year ago

myininayaBest ResponseYou've already chosen the best response.2
omg lol I said increasing by 8 and then continue to think the thingy was increasing by 8 sometimes i wonder about myself lol
 one year ago
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