Site navigation

If \(8x^2 - 2kx + k = 0\) is a quadratic equation in \(x\), such that one of its roots is \(p\) times the other, and \(p, k\) are positive real numbers, then \(k\) equals

Question and options

If 8x2−2kx+k=08x^2 - 2kx + k = 0 is a quadratic equation in xx, such that one of its roots is pp times the other, and p,kp, k are positive real numbers, then kk equals
  1. (p+1p)(p + \frac{1}{p})
  2. 2(p+1p)2(p + \frac{1}{p})
  3. 2(p+1p)22(\sqrt{p} + \frac{1}{\sqrt{p}})^2
  4. (p+1p)2(\sqrt{p} + \frac{1}{\sqrt{p}})^2

Answer and explanation

Correct answer: C - \(2(\sqrt{p} + \frac{1}{\sqrt{p}})^2\)
Roots r and pr: r(1+p) = k/4 and p r^2 = k/8. Eliminating r: k^2/16 = k(1+p)^2/(8p), so k = 2(1+p)^2/p = 2(sqrt(p)+1/sqrt(p))^2.

Practice for these exams

  • IPMAT Indore

Related question papers

Related exam syllabi

More solved explanations in Arithmetic