Question 119
If $(a, b)$ is the solution of the system
$$\sqrt{x+y} + \sqrt{x-y} = 4,$$
$$x^{2} - y^{2} = 9,$$
then $\frac{a b}{a+b}$ has value
(a) $\frac{10}{9}$
(b) $\frac{8}{3}$
(c) $10$
(d) $\frac{20}{9}$
$$\sqrt{x+y} + \sqrt{x-y} = 4,$$
$$x^{2} - y^{2} = 9,$$
then $\frac{a b}{a+b}$ has value
(a) $\frac{10}{9}$
(b) $\frac{8}{3}$
(c) $10$
(d) $\frac{20}{9}$