Given that A and B, where A < B, are the roots of the equation 2x^2 + x -5 = 0
Calculate the value of
(c) A - B [Answer = -1/2 Sqrt 41]

Sum of roots = A + B = 1/2
Product of roots = AB = -5/2

I have tried to use A^2 - B^2 / A + B, but I can't seem to get +B^2, since all expansions of (A-B)^2 and (A+B)^2 involve B^2

2. \begin{aligned}\begin{array}{c} (a+b)^2 = a^2+2ab+b^2\\\ (a-b)^2 = a^2-2ab+b^2 \end{array} & \iff (a+b)^2-(a-b)^2 = 4ab.\end{aligned}