Expansion of power series f(x)= 9/(1+x)^(1/2)

9-(9x/4)+ series from n=2 to infinity 9(-1)^n ((1 x 5 x 9 .... (4n-3))X^n)/(4^n x n!)

I have to use this series to estimate 9 / (1.5)^(1/4) correct to three decimal places. This means x= 0.5

(by x I mean multiplication (except the capital X, which stands for X), and I know I should use a dot to represent multiplication, but I couldn't do it.)

Please help me.
Thanks.