Let z be a complex number with non-zero imaginary part. If 2 + 3 z + 4 z 2 2 - 3 z + 4 z 2 is a real number,…

Let z be a complex number with non-zero imaginary part. If 2+3z+4z22-3z+4z2 is a real number, then the value of z2 is ______.

Solution

Let α=4z2+3z+24z2-3z+2=1+6z4z2-3z+2

 α=1+622z+1z-3

 αR then 2z+1zR

2z+1z=2z¯+1z¯

2z-z¯-z-z¯z2=0

z-z¯2-1z2=0

 zz¯  (given)

So z2=12=0.5

Asked in: JEE Advanced 2022 (Paper 1)

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