Complex Numbers And Quadratic Equations question 532

Question: If the roots of the equation $ \frac{\alpha }{x-\alpha }+\frac{\beta }{x-\beta }=1 $ be equal in magnitude but opposite in sign, then $ \alpha +\beta $ =

Options:

A) 0

B) 1

C) 2

D) None of these

Show Answer

Answer:

Correct Answer: A

Solution:

Given equation $ \frac{\alpha }{x-\alpha }+\frac{\beta }{x-\beta }=1 $ can be written as Þ $ x^{2}-2(\alpha +\beta )x+3\alpha \beta =0 $ Let roots are $ {\alpha }’ $ and $ -{\alpha }’ $ $ {\alpha }’+(-{\alpha }’)=2(\alpha +\beta )\Rightarrow 0=2(\alpha +\beta )\Rightarrow \alpha +\beta =0 $ .