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Mathematics 11 Online
OpenStudy (anonymous):

. Find the sum.

OpenStudy (anonymous):

of?

OpenStudy (anonymous):

\[\sum_{100}^{n=1}7n\]

OpenStudy (anonymous):

how do you do this?

OpenStudy (anonymous):

waittt this is backwardsss

OpenStudy (anonymous):

good question im sorry i cnt help you love

OpenStudy (zarkon):

\[\sum_{n=1}^{k}an=a\frac{k(k+1)}{2}\]

OpenStudy (anonymous):

\( \sum \limits_{100}^{n=1}7n \); is meaningless but \( \sum \limits_{n=1} ^{100}7n \) is an arithmetic progression.

OpenStudy (anonymous):

\( \huge \sum \limits_{n=1} ^{100}7n = 35350 \)

OpenStudy (anonymous):

thank you foolformath! but how exactly did you do this?

OpenStudy (anonymous):

See, Zarkon's answer.

OpenStudy (zarkon):

\[7\frac{100(100+1)}{2}=35350\]

OpenStudy (anonymous):

so if i had this equation,\[\sum_{n=1}^{100}2n\] my answer would be 10100 am i right?

OpenStudy (zarkon):

yes

OpenStudy (anonymous):

ohhh ok thanks!

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