Complex Numbers And Quadratic Equations question 407

Question: The values of $ x $ and $ y $ satisfying the equation $ \frac{(1+i)x-2i}{3+i} $ $ +\frac{(2-3i)y+i}{3-i}=i $ are [IIT 1980; MNR 1987]

Options:

A) $ x=-1,y=3 $

B) $ x=3,y=-1 $

C) $ x=0,y=1 $

D) $ x=1,y=0 $

Show Answer

Answer:

Correct Answer: B

Solution:

$ \frac{(1+i)x-2i}{3+i}+\frac{(2-3i)y+i}{3-i}=i $
Þ $ (4+2i)x+(9-7i)y-3i-3=10i $ Equating real and imaginary parts, we get $ 2x-7y=13 $ and $ 4x+9y=3 $ . Hence $ x=3 $ and $ y=-1 $ . Trick : After finding the equations, no need to solve them, put the values of $ x $ and $ y $ given in the options and get the appropriate option.