(d) Here, $a = (p - q),\ b = 5(p + q)$ and $c = - (2p - 2q + r)$ Now, $b^{2} - 4ac = 25(p + q)^{2} + 4(p - q)(2p - 2q + r)$ $= 25(p + q)^{2} + 8(p - q)^{2} + 4r(p - q)$ Hence, it depends on the value of $p,\ q$ and $r$
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.