Sigma Percentile
JEE Main 2024 (04 Apr Shift 1)
LEVELJEE Main

Animated Solution for Mathematics - Complex Numbers: Let and be the sum and the product of all the non-zero solutions of the equation . Then is equal to :

Select Answer:

Visualized Solution

Defining

  • Let the complex number be , where .
  • The conjugate is .
  • The modulus is .

Substituting into

  • Original Equation:
  • Substitute and :

Expanding

  • Expand using :
  • Since :

Separating Real and Imaginary Parts

  • Group real and imaginary terms:
  • Set Real part to zero:
  • Set Imaginary part to zero:

Solving

  • From , we have two cases:
  • Case 1:
  • Case 2:

Case 1:

  • Substitute into the Real part equation:

Solutions for Case 1

  • Factorize:
  • Possible values: or
  • For non-zero solutions,
  • Solutions: and

Case 2:

  • Substitute into the Real part equation:

Analyzing Case 2

  • Since , then .
  • Thus, .
  • The only solution is .
  • This gives , which is rejected (we need non-zero solutions).

Calculating Sum and Product

  • Non-zero solutions:
  • Sum
  • Product

Final Evaluation

  • Expression to evaluate:
  • Substitute and :
  • The final value is 4.

The Sigma Insight: Algebraic Operations on Complex Numbers

Solution Diagram

The Geometry of Complex Equations

Welcome, fellow explorer of the complex plane! Today, we are going to dismantle a beautiful problem that might look intimidating at first glance, but reveals a stunning symmetry once we peel back the layers.
We are dealing with the equation . At first, it looks like a jumble of conjugates and moduli, but we are going to use the most reliable tool in our JEE arsenal: the Cartesian representation.

The Cartesian Foundation

Whenever you see an equation involving , , and , do not panic. The safest, most systematic approach is to define , where and are real numbers.
This immediately gives us the conjugate and the modulus . By substituting these into our original equation, we transform a complex-variable problem into a system of real-variable equations.

The Expansion and the Trap

Let us substitute our definitions into the equation:
Now, we expand the squared term. Since , our equation becomes:
We group the real and imaginary parts:
For this complex number to be zero, both the real part and the imaginary part must vanish independently. This gives us two crucial equations:

The Bifurcation of Cases

Look at the imaginary part: . This is a gift! It tells us that either or .
Case 1: Substituting this into our real part equation, we get . Since , we have .
Factoring this, we get . This gives us (which leads to ) or . Thus, , yielding non-zero solutions and .
Case 2: Substituting this into the real part equation, we get , which simplifies to . Since , the only solution is , which leads to . We reject this as it is not a non-zero solution.

The Final Victory

We have found our non-zero solutions: and . The problem asks for the sum and the product of these solutions.
The sum . The product .
Finally, we evaluate the expression :
We have arrived at the answer! The final result is 4.

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