Find the sum of the first 12 terms of the sequence. show all work for full credit. 1, -4, -9, -14, . .

 find the common difference, subtract the first term from the second term.
-4 - 1 = -5so the common difference is -5.

now we will find the 12th term...we need to know this in order to find the sum.
an = a1 + (n-1) * d
n = term we want to find = 12
a1 = first term = 1
d = common difference = -5
now we sub
a12 = 1 + (12 - 1) * -5
a12 = 1 + 11 * -5
a12 = 1 - 55
a12 = - 54

now we use the sum formula
sn = (n(a1 + a12) / 2
s12 = 12 (1 - 54) / 2
s12 = 12(-53)/2
s12 = -636/2
s12 = - 318 <

The expressions would be 0.25a

Most of the people don’t make the sense of taking it