Theory of Equations 1 Question 22

23. Let α,β be the roots of the equation x2px+r=0 and α2,2β be the roots of the equation x2qx+r=0. Then, the value of r is

(2007,3M)

(a) 29(pq)(2qp)

(b) 29(qp)(2pq)

(c) 29(q2p)(2qp)

(d) 29(2pq)(2qp)

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Answer:

Correct Answer: 23. (d)

Solution:

  1. The equation x2px+r=0 has roots α,β and the equation x2qx+r=0 has roots α2,2β.

r=αβ and α+β=p

and α2+2β=qβ=2qp3 and α=2(2pq)3

αβ=r=29(2qp)(2pq)



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