Question

if first second and last terms of ap are a,b,2a then its sum will be

Answer 1

Answer:

Step-by-step explanation:

Answer of ur ques is- 3ab / 2(b-a)

A.P : a , b , . . . . . . . . . . . . . .2a

1st term= a1 = a

2nd term = a2= b

nth term = an = 2a

d = a2 - a1 = b-a

an = a1 + (n-1)d = a + (n-1)(b-a) = 2a

(n-1)(b-a) = a

(n-1) = a / (b-a)

n = a / (b-a) + 1 = b / ( b -a )

Sn = n / 2 * ( a1 + an) = b / 2(b-a) * ( a + 2a) = 3ab / 2(b-a)

Hope this helps! Cheers!!

Read more on Brainly.in - https://brainly.in/question/1559503#readmore