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what is the sum of the first 24 terms of the sequence 80, 72, 64, ...?

a. 4128
b. 3168
c. 1248
d.-288


Sagot :

D. -288

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Answer:

d-288

Step-by-step explanation:

Solve for common difference

d = a2-a1

d = 72–80

d = –8

Solve for a24

an = a1+(n-1)d

a24 = 80 +(24-1)(-8)

a24 = 80 –184

a24 = –104

Solve for the Sum(S24)

Sn = n/2(a1+an)

S24 = 24/2(80+(-104))

S24 = 12(80-104)

S24 = 12(–24)

S24 = –288