Question

what is the sum of first n terms of AP a,3a,5a

Answer 1

S=(2an+3a)/2, as d=2a, a=a,n is unknown

Answer 2

Answer:

Sum of n term = Sn = n/2 ( 2 a + ( n - 1) d/2)

Step-by-step explanation:

First Term = a

Second term = 3 a

Common Difference = Second term - first term

= 3 a - a = 2 a

Sum of n term = Sn = n/2 ( 2 a + ( n - 1) d/2)

You can calculate the sum only if last term of the A.P is given or no. of term of an A.P is given.