Pls help. All help appreciated.

By Vieta's, we have:

 

$-a = 2a + 2b$                   (i)

$b = 4ab$                          (ii)

 

From the second equation, we have $a = {1 \over 4}$. 

 

Subbing this into (i) gives us $b = -{3 \over 8}$

 

Thus, $a + b = {1 \over 4} - {3 \over 8} = \color{brown}\boxed{-{1 \over 8}}$