Question

find the sum of 2 + 5 + 8 + ...............+ 48​

Answer 1

Given:

a ( first term ) = 2

d ( common difference ) = 3

an ( Last Term ) = 48

To Find:

The sum of the A.P.

Formula:

an = a + ( n - 1 )d

S = n/2 ( a + an )

Solution:

48 = 2 + ( n - 1 )3

or, 48/3 =2 + ( n - 1 )

or, 16 - 2 = n - 1

or, 14 + 1 = 15 = n

S = 15/2 ( 2 + 48 )

S = 15 ( 25 )

S = 375

Answer:

The sum of the A.P. is 375.