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Mathematics 20 Online
OpenStudy (ashleyisakitty):

Check my answer please :~) What is the sum of the arithmetic series 18Σt-1(5t-4).

OpenStudy (ashleyisakitty):

I got 1566.

OpenStudy (amistre64):

might need to clarify your notation

OpenStudy (ashleyisakitty):

\[\sum_{t-1}^{18}(5t-4)\]

OpenStudy (amistre64):

5(1) - 4 5(2) - 4 5(3) - 4 ... 5(18)-4 ------- vv -4(18 times) 5(1+2+3+...+18))

OpenStudy (amistre64):

5(18)(19)/2 - 4(18) thats better

OpenStudy (amistre64):

from 1 to 18 right? if so, its not 1566

OpenStudy (ashleyisakitty):

783?

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