Derivative of $(2x-1)(x+3)^{\frac{1}{2}}$ Find the derivative of 
$(2x-1)(x+3)^{\frac{1}{2}}$ 
My try - 
$(2x-1)(\frac{1}{2} (x+3)^{\frac{-1}{2}} (x+0) + (x+3)^{\frac{1}{2}} (2)$ 
$ = (x+3)^{\frac{-1}{2}} (\frac{1}{2}(2x-1) + 2(x+3) $ 
$= \frac{3x+5.5}{2 (x+3)^{\frac{1}{2}}} $ 
My numerator is wrong and should be 
$6x+11$ . Where did I go wrong ? Thanks !! 

you did wrong in the first step, the derivate of (x+3) is equal to 1. 
