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Mathematics 15 Online
OpenStudy (sleepyjess):

Find the sum of the arithmetic sequence. -10, -7, -4, -1, 2, 5, 8

OpenStudy (sleepyjess):

@phi

OpenStudy (alexandervonhumboldt2):

is it infinite?

OpenStudy (alexandervonhumboldt2):

if no then -10-7-4-1+2+5+8

OpenStudy (sleepyjess):

-7

OpenStudy (welshfella):

one formula you can use is Sn = n/2{a1 + L] where n = no. of terms a1 = first term and L = last term

OpenStudy (sleepyjess):

thanks both of you :)

OpenStudy (welshfella):

or you can just add them up of course! yw

OpenStudy (sleepyjess):

I realized what to do right after I posted it haha

OpenStudy (alexandervonhumboldt2):

yeah

OpenStudy (sleepyjess):

but I like the formula, I can use it whenever in case there are a lot of terms

OpenStudy (welshfella):

lol - i didn't think of just adding them up!

OpenStudy (welshfella):

yes its useful when you are given the last term

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