Question

If the first, second and last term of an A.P are a, b and 2a respectively. Its sum is​

Answer 1

Answer:

Step-by-step explanation:

t1= a

t2=b

t3=l =2a

∴ $S_{n}$ = $\frac{n}{2}$(a+l)

S3 = 3/2(a+2a)

s3=3/2*3a

s3=9/2a