SOLUTION: Find the first term and the common difference of the arithmetic sequence whose 7th term is -30 and 12th term is -55. first term common difference

Algebra ->  Sequences-and-series -> SOLUTION: Find the first term and the common difference of the arithmetic sequence whose 7th term is -30 and 12th term is -55. first term common difference      Log On

There are 5 gaps between the 7th term and 12th term.


Therefore, the common difference is   d =  = -5.


Then  from   =  + 6*d you have


     =  - 6*d = -30 - 6*(-5) = -30 + 30 = 0.