Question 2For each pair of real numbers $a \neq b,$ define the operation $\star$ as $$ (a \star b) = \frac{a+b}{a-b}. $$ What is the value of $((1 \star 2) \star 3)?$$-\dfrac{2}{3}$$-\dfrac{1}{5}$$0$$\dfrac{1}{2}$This value is not defined.