Question

in an ap , if a=5, d = 2.5 , an=10 , then find the value of n

Answer 1

An= a + ( n - 1) d
10 = 5 + ( n - 1 ) * 2.5
10 = 5 + 2.5n - 2.5
10 = 2.5 n + 2.5
2.5 n = 7.5
n = 3.

Answer 2

Given :-

a = 5

d = 2.5

an = 10

n = ?

We have a formula to find the digit ( A.P ) on the nth term !

=> an = a + ( n - 1 )d

10 = 5 + ( n - 1 ) × 2.5

10 = 5 + 2.5n - 2.5

10 = 2.5 + 2.5n

10 - 2.5 = 2.5n

7.5 = 2.5n

3 = n


So, the nth term of A.P is 3

For which it have 10 as term value.