The least positive value of $k$, for which the quadratic equation $2 x^{2}+k x-4=0$ has rational roo

Question

The least positive value of $k$, for which the quadratic equation $2 x^{2}+k x-4=0$ has rational roots, is\

Professor PC Thomas Classes · Answer

(b):For rational roots, $D$ is a perfect square $$ \begin{aligned} & D=k^{2}+32 \ & 	ext { If } k=2 	ext { then, } \ & D=2^{2}+32=36, 	ext { which is a perfect square } \end{aligned} $$