Let α = 8 - 14 i ,    A = z ∈ ℂ : α z - α ¯ z ¯ z 2 - ( z…

Let α=8-14i,  A=z:αz-α¯z¯z2-(z¯)2-112i=1 and B=z:z+3i=4

Then, zAB(Rez-Imz)   is equal to  ________

Solution

Given:

A=z:αz-α¯z¯z2-(z¯)2-112i=1

B=z:z+3i=4

α=8-14i

Let

z=x+iy

So,

αz=8-14ix+iy

αz=(8x+14y)+i(-14x+8y)

Also,

z+z¯=2x and z-z¯=2iy

Set A:

αz-α¯z¯z2-(z¯)2-112i=1

2i-14x+8yz+z¯z-z¯-112i=1

2i-14x+8y4ixy-112i=1

 -14x+8y2xy-56=1

xy+7x-4y-28=0

x-4y+7=0

x=4 or y=-7

Set B:

z+3i=4

x+iy+3=4

x2+y+32=16

When x=4y=-3

When y=-7x=0

AB=4-3i,0-7i

So, zABRez-Imz=4-(-3)+(0-(-7))=14

Asked in: JEE Main 2023 (29 Jan Shift 2)

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