Question

An arithmetic sequence has a first term of 0 and the 9th term of 12. If 27 is an output of the sequence, which term number is it? Show all steps of calculations and explain in a sentence at the end how you know you have the correct term number.

Giving 100 points to first correct answer

Answer 1

Explanation:

`a_(n)=a_(1)+(n-1) d\\n=9\\12=0+(9-1)d\\8d=12\\d=(12)/(8)=(3)/(2)\\again\\27=0+(n-1)*(3)/(2)\\n-1=27*(2)/(3)=18\\n=18+1=19`