Question 462232
What is the sum of a 17–term arithmetic sequence where the first term is 6 and the last term is –90?
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To find the SUM of the series we'll use
{{{S[n]=(n(a[1]+a[n]))/2}}}
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a[1] = the first term = 6
n = the number of terms we're interested in = 17
a[n] = the nth term; in this case, the 17th term = -90
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To find the sum of the series we'll use,
{{{S[n]=(n(a[1]+a[n]))/2}}}
{{{S[17]=((17)(6+(-90)))/2}}}
{{{S[17]=-714}}}
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hope this helps!
Ms.Figgy
math.in.the.vortex