Question

Q.9

Answer 1

12, a+b and 2a are in AP.

`⇒ a+b=(12+2a)/2`

`⇒a+b=6+a`

`⇒b=6`

And , 

a+b, 2a and b are in A.P. 

`⇒2a=(a+b+b)/2`

`⇒4a=a+2b`

`⇒3a=2b`

`⇒ a=(2b)/3`

`⇒a=(2xx6)/3=4`

Hence, `a=4 and b=6`