(a) We have, pair of line is px2−qy2 = 0 ...(i) After comparing eq. (i) with ax2+2hxy+by2 = 0, we get a = p, b = -q, h = 0 As slopes of pair of lines represented by ax2+2hxy+by2 = 0 are real and distinct iff h2−ab > 0 So, 0 + p q > 0 Hence, pq > 0