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Let left|z_1 - 8 - 2iright| leq 1 and left|z_2 - 2 + 6iright| leq 2 , z_1, z_2 in C . Then the minimum value of left|z_1 - z_2 ight| is:

Solution & Explanation

### Related Formula textMinimum distance between two circles: d_textmin = C_1C_2 - r_1 - r_2 ### Core Logic The expressions define two circular disc fields in the complex plane: Circle 1: Center C_1(8, 2), radius r_1 = 1 Circle 2: Center C_2(2, -6), radius r_2 = 2
Geometry of Complex Numbers diagram for Q69 - JEE Main 2025 Morning
Geometry of Complex Numbers diagram for Q69 - JEE Main 2025 Morning
### Step 1: Calculate Center Distance Using coordinate distance formulation: C_1C_2 = sqrt(8 - 2)^2 + (2 - (-6))^2 = sqrt6^2 + 8^2 = 10 ### Step 2: Find Minimum Separation |z_1 - z_2|_textmin = C_1C_2 - r_1 - r_2 = 10 - 1 - 2 = 7 ### Pattern Recognition Always interpret modulus circle properties geometrically rather than algebraically. Disconnecting complex plane variables into simple 2D analytical geometry centers avoids calculation mistakes entirely. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Mathematics: Complex Numbers Class 11 Mathematics: Coordinate Geometry

Reference Study Guides

More Complex Numbers Previous-Year Questions — Page 3

Q56 2025 Algebraic Properties of Complex Roots
If alpha and beta are the roots of the equation 2z^2 - 3z - 2i = 0 , where i = sqrt-1 , then 16 cdot mathrmReleft(fracalpha^19 + beta^19 + alpha^11 + beta^11alpha^15 + beta^15right) cdot operatornameImleft(fracalpha^19 + beta^19 + alpha^11 + beta^11alpha^15 + beta^15right) is equal to :
  • A. 398
  • B. 312
  • C. 409
  • D. 441

Solution

### Related Formula Since alpha and beta are roots of 2z^2 - 3z - 2i = 0, they satisfy the quadratic equation directly, meaning: 2alpha^2 - 3alpha - 2i = 0 implies 2left(alpha - fracialpharight) = 3 implies alpha - fracialpha = frac32 Similarly for beta: beta - fracibeta = frac32 ### Core Logic Square the baseline relation to transition to higher exponential powers: left(alpha - fracialpharight)^2 = left(frac32right)^2 implies alpha^2 - frac1alpha^2 - 2i = frac94 alpha^2 - frac1alpha^2 = frac94 + 2i Squaring once more to isolate the fourth powers: left(alpha^2 - frac1alpha^2right)^2 = left(frac94 + 2iright)^2 alpha^4 + frac1alpha^4 - 2 = frac8116 - 4 + 9i alpha^4 + frac1alpha^4 = frac4916 + 9i ### Step 1: Simplify the Target Expression Fraction Rearrange the given complex algebraic fraction by factoring out powers: fracalpha^19 + alpha^11 + beta^19 + beta^11alpha^15 + beta^15 = fracalpha^15left(alpha^4 + frac1alpha^4right) + beta^15left(beta^4 + frac1beta^4right)alpha^15 + beta^15 Since both alpha and beta satisfy the exact same symmetric relational identity: alpha^4 + frac1alpha^4 = beta^4 + frac1beta^4 = frac4916 + 9i Substitute this uniform value back into the algebraic expression: = frac(alpha^15 + beta^15)left(frac4916 + 9iright)alpha^15 + beta^15 = frac4916 + 9i ### Step 2: Extract Real and Imaginary Components From our simplified expression: mathrmRe = frac4916 operatornameIm = 9 Now, substitute these into the evaluation formula: textResult = 16 cdot left(frac4916right) cdot 9 = 49 cdot 9 = 441 ### Pattern Recognition Symmetric rational polynomials in roots alpha, beta that can be split into identical numeric multipliers for alpha^n and beta^n allow direct cancellation of the polynomial bases without evaluating the individual roots explicitly. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Mathematics: Complex Numbers

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