Question

Find the sum of the first 12 terms of the sequence. Show all work for full credit.

1, -4, -9, -14, . . .

Answer 1

this is arithmetic sequence,
the sum of the n first term is
\[Sn = \frac{ n }{ 2 }\left( 2a + \left( n-1 \right) d \right)\]
with
n = the number of terms
a = the first term
d = the difference

you can use this formula to solve the problem
can you determine, what is n, a, and d of your sequence?

Answer 2

d=-9-(-4)
=-9+4
=-5
n=12
a=1.

Answer 3

yess... :)
now, plug in the value into the formula...

Answer 4

12/2(2*1+(12-1)-5)

Answer 5

which equals 48?

Answer 6

be careful in calculation.... :)