Answer:
Method 1:
OA: 63/16
p, q, r, s are in HP
Put x->1/x then roots in AP
x^2 - 4x + A = 0 and
x^2 - 6x + B = 0
Let roots be a-3d, a-d, a+d, a+3d
2a - 4d = 4
2a + 4d = 6
a= 5/2; d = 1/4
A = (a-3d)(a-d) = 63/16
B = (a+d)(a+3d) = 143/16
Method 2:
(p+q)/pq = 1/p+1/q = 4
Similarly 1/r+1/s = 6., 1/p, 1/q, 1/r, 1/s in Ap. So find p, q and find A using p+q = 4/A
p, q, r, s are in HP
Put x->1/x then roots in AP.