SOLUTION: Determine the number of terms in an arthmetic sequence with t3= -17.5 and t10= -52.5. the final term in the sequence is -147.5

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Question 993264: Determine the number of terms in an arthmetic
sequence with t3= -17.5 and t10= -52.5. the
final term in the sequence is -147.5
Answer by Edwin McCravy(20056)   (Show Source): You can put this solution on YOUR website!
Determine the number of terms in an arthmetic
sequence with t3= -17.5 and t10= -52.5. the
final term in the sequence is -147.5


Substitute n=3 and t3=-17.5





Substitute n=10 and t10=-52.5





Now we have a system of equations:



Solve that system and get t1=-7.5, d=-5

the final term in the sequence is -147.5

Substitute t1=-7.5, d=-5 and tn=-52.5
in the same formula



Solve that and get n = 10

Edwin
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