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Question

Question: If the roots of equation \(\frac{1}{x + p} + \frac{1}{x + q} = \frac{1}{r}\) are equal in magnitude ...

If the roots of equation 1x+p+1x+q=1r\frac{1}{x + p} + \frac{1}{x + q} = \frac{1}{r} are equal in magnitude but opposite in sign, then (p+q)=(p + q) =

A

2r

B

r

C

– 2r

D

None of these

Answer

2r

Explanation

Solution

Given equation can be written as

x2+(p+q2r)x+[pq(p+q)r]=0x^{2} + (p + q - 2r)x + \lbrack pq - (p + q)r\rbrack = 0

Since the roots are equal and of opposite sign,

∴ Sum of roots = 0

(p+q2r)=0- (p + q - 2r) = 0p+q=2rp + q = 2r