given that the first term of an Ap is 7 and its 10th term is twice the second term calculate the 19th term.

7 answers

a = 7
a+9d = 2(a+d)
9d +a = 2a+ 2d
7d = a
7d=7
d=1

19th term = a+18d =7+18(1) = 25
a=7,a+9d=2(a+d),9d+a=2a+2d,7d=9,7d= 7,d=1,19th term=a+18d=7+18(1)=25
14
Sum of 28 terms
Good
ALSO SUM OF 28TH
19th term =25
Sum of the 28th term=574