Question:

If \(a ≠ ±b\) and are purely real, z ϵ complex number, \(Re(az^{2}+bz)=a\) and \(Re(bz^{2}+az)=b\) then number of value of z possible is

Updated On: Mar 21, 2025
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The Correct Option is A

Approach Solution - 1

\(a(x^2-y^2)+bx=a…..(i)\)
\(b(x^2-y^2)+ax=b…..(ii)\)
\((i)-(ii)\)
\((a-b)(x^2-y^2)+(b-a)x=a-b\     \      \        \  (a≠b)\)
\(⇒ x^2-y^2-x=1\)
\((i)+(ii)\)
\((a+b)(x^2-y^2)+x(a+b)=a+b\)        \( (a≠-b)\)
\(⇒ x^2-y^2+x=1\)
\(⇒x=0\)
\(⇒y^2=-1\)
therefore, no complex number is possible.
The correct option is (A): 0

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Approach Solution -2

We are given the conditions for the real and imaginary parts of \( z \). Let \( z = x + iy \), where \( x \) and \( y \) are real numbers. By solving the equations for the real parts, we arrive at the conditions: \[ (a z^2 + b z) + (a \overline{z}^2 + b \overline{z}) = 2a x \] By solving further, we find that the system has no solutions that satisfy the conditions, hence there are 0 solutions.
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Concepts Used:

Complex Number

A Complex Number is written in the form

a + ib

where,

  • “a” is a real number
  • “b” is an imaginary number

The Complex Number consists of a symbol “i” which satisfies the condition i^2 = −1. Complex Numbers are mentioned as the extension of one-dimensional number lines. In a complex plane, a Complex Number indicated as a + bi is usually represented in the form of the point (a, b). We have to pay attention that a Complex Number with absolutely no real part, such as – i, -5i, etc, is called purely imaginary. Also, a Complex Number with perfectly no imaginary part is known as a real number.