How is it 9*(1/2) and and 3.0 is came ?

Answer 1

9**(1/2)==3
9**(1/2)=9^(1/2)=9^.5=sqrt(9)=3. Float 3.0

Answer 2

9*(1/2) does not equal 3.0, it equals 4.5

As J.G. says
9**(1/2) = 3.0
9**(1/2) = 9^(1/2) = sqrt(9) = 3.0

* is multiplication
** is exponentiation

also the answer is a float because division (1/2) always results in floats.