What is the first term if the 10th term of an arithmetic sequence is 39 and the 15th term is 59
What is the first term if the 10th term of an arithmetic sequence is 39 and the 15th term is 59
Use the formula for the nth term:
39 ==F + 9D...................(1), where F==First term, D==Common difference
59 ==F + 14D..................(2), solve for F, D
Use substitution to get:
F==3 and D == 4
Your sequence looks like this:
3 , 7 , 11 , 15 , 19 , 23 , 27 , 31 , 35 , 39 , 43 , 47 , 51 , 55 , 59 , >>Number of terms = 15>>Total Sum == 465
