Question

If the equation p(q – r)x² + q(r – p)x + r(p – q) = 0 has equal roots, then 2/q is equal to

(a)  1/p + 1/r

(b)  p + r

(c)  1/p + r

(d)  p + 1/r

Answer 1

Correct option  (a)  1/p + 1/r

Explanation:

Clearly x = 1 is one root and the other root  is r(p - q)/p(q - r)

∴ roots are equal, we have r(p - q)/p(q - r) = 1

(∴  Product of roots = r(p - q)/p(q - r))

⇒  rp – rq = pq – rq

2rp = pq + rq

2/q = 1/p + 2/r