Given, equation of parabola is y2=8x ......(i) ∴ a=2 Let (h,4) be the coordinate of mid-point of chord. Then, equation of chord is y−4=m(x−h) ......(ii) If line (ii) passes through the point P(2t12,4t1) and Q(2t22,4t2) on parabola Eq. (i), then y(t1+t2)−2x−4t1t2=0 .......(iii) having slope m=
2
t1+t2
......(iv) Since, (h,4) is the mid-point of PQ. Therefore, 2×4=4(t1+t2) ⇒ t1+t2=2 Hence, slope of chord PQ ism=