Question
Mathematics Question on Algebra of Complex Numbers
Reflection of the line aˉz+azˉ=0 in the real axis is given by
A
az+azˉ=0
B
aˉz−azˉ=0
C
az−azˉ=0
D
za+zaˉ=0
Answer
az+azˉ=0
Explanation
Solution
The correct answer is option (A): a z+a zˉ=0
let a=α+iβ
z=x+iy
Now, aˉz+azˉ=0
⇒(α−iβ)(x+iy)+(α+iβ)(x−iy)=0
slope=−βαx
So, reflection slope = βαx
Line is αx−βy=0→reflection also passes through origin
⇒(2a+aˉ)(2z+zˉ)−(2ia−aˉ)(2iz−zˉ)=0
⇒az+azˉ=0