3 differences (7 to 10) is 9
so d = 9 / 3 = 3
the 7th term is 6 differences from the 1st term
...1st + (3 * 6) = 7th
...1st + 18 = 19
so the 1st three terms are
...1, 4, 7
The 10th term of an arithmetic progress in 28 and the 7th term is 19.calculate the 1st,2nd and 3rd terms of the progression
1 answer