Question 670823
Using the quadratic formula on the first one we get:

{{{x= (-a +-sqrt(a^2 - 4*1*2b))/(2) = (-a +-sqrt(a^2 - 8b))/(2)}}}

Second:

{{{x = (-2b +- sqrt(4b^2 - 4a))/(2) = (-2b +- 2sqrt(b^2-a))/(2) = (-b +-sqrt(b^2-a))}}}

Which when set equal to each other we get b = (a/2) and so  b = 2 and a = 4

So a+b = 6