what is the sum of the sequence 152,138,124, ... if there are 24 terms?
Accepted Solution
A:
Answer: -216Step-by-step explanation: To solve the exercise you must use the formula shown below: [tex]Sn=\frac{(a_1+a_n)n}{2}[/tex] Where: [tex]a_1=152\\a_n=a_{24}[/tex] You should find [tex]a_{24}[/tex] The formula to find it is: [tex]a_n=a_1+(n-1)d[/tex] Where d is the difference between two consecutive terms. [tex]d=138-152=-14[/tex] Then: [tex]a_{24}=152+(24-1)(14)=-170[/tex] Substitute it into the first formula. Therefore, you obtain: [tex]S_{24}=\frac{(152-170)(24)}{2}=-216[/tex]