Question

the 7th and 13th terms of an ap are 34 and 64 respectively then it's first term and common difference are____​

Answer 1

Answer:

Let 1st term be "a" and common difference be "d" then 7 term and 13 term can be written as a+6d=34......equ.(1) a+12d=64......equ.(2) Solve both equ. We get a=4 & d=5 then So, 18 term be a+17d= 4+17 5 = 89 And.

Answer 2

It is very easy and interseting sum