Question

PLEASEE HELP MEEE!:/
What is the sum of the arithmetic sequence 149,135,121,..., if there are 28 terms?
a. -1,204
b.-1,176
c. -1,148
d. -1,120

Answer 1

keep subtracting 14 i think

Answer 2

i did but then it become negative & gets lower:/ get me?

Answer 3

the ancer is D -1220

Answer 4

answer

Answer 5

yes D i the answer

Answer 6

S = (n/2) × (2a + (n-1)d) This is the formula
s=(28/2)*((2*149)+(28-1)*-14)=-1120

Answer 7

sorry n stands for the number of terms in the sequence,
a- first term
d- difference

Answer 8

thank you so much!