Question

The second term of an arithmetic sequence is18 and it's 4 th term is 32. write it's third and first term?

Answer 1

Here, a= ? ,d= ? and a3= ?
and, second term of an a.p is = 18
then, we can say , a + d = 18 ...........(1)
and 4th term of an a.p = 32
it can be say as , a + 3d = 32 ............(2)
now, subtracting eq. 2 from 1 , then we obtain ,
a + d = 18
a + 3d= 32
- - -
_______
-2d = -14
d = -14/-2
d = 7
now put the value in eq. (1)
so , a + 7 = 18
then a = 18 - 7 = 11
now , 3rd term is = a + 2d
so, 11 + 2(7) = 11 + 14 = 25
So , first term is 11 and third term is 25. Ans.