# math

The 9th term of an AP is 52 while the 12 term is 70 find the sum of the 20 terms.

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3. 👁 80

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posted by Abu
2. https://www.mathsisfun.com/algebra/sequences-sums-arithmetic.html

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posted by Damon
3. a+8d = 52
a+11d = 70
Now find a and d, and then
S20 = 20/2 (2a+19d)

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posted by oobleck

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