Let z be a complex number such that |z| = 1. If frac2 + k^2zk + overlinez = kz, k in mathbbR, then the maximum distance of k + ik^2 from the circle |z - (1 + 2i)| = 1 is:

Solution & Explanation

### Related Formula For a complex number lying on the unit circle: |z| = 1 implies zoverlinez = 1 implies overlinez = frac1z Maximum distance from a point P to a circle with center C and radius r is: d_max = PC + r ### Core Logic Simplify the algebraic condition using overlinez = 1/z to uniquely determine the value of the parameter k, then compute geometric distances. ### Step 1: Solve for k Cross-multiply the given expression: 2 + k^2z = kz(k + overlinez) = k^2z + kzoverlinez Since zoverlinez = |z|^2 = 1: 2 + k^2z = k^2z + k(1) implies k = 2 ### Step 2: Locate Point and Circle Parameters Substitute k=2 into the target point expression P = k + ik^2: P = 2 + 4i equiv (2,4) The circle equation is |z - (1 + 2i)| = 1, which represents a circle centered at C = (1, 2) with radius r = 1. ### Step 3: Compute Geometric Distances Find the Euclidean distance between P(2,4) and center C(1,2): PC = sqrt(2-1)^2 + (4-2)^2 = sqrt1 + 4 = sqrt5 The maximum distance from the point to the circle boundary is: d_max = PC + r = sqrt5 + 1 ### Pattern Recognition Notice how k^2z cancels perfectly on both sides during expansion due to the unique property of uni-modular complex numbers (zoverlinez=1), rendering the calculation of k trivial. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Mathematics: Complex Numbers and Quadratic Equations

More Complex Numbers and Quadratic Equations Previous-Year Questions — Page 7

Q26 jee_main_2024_31_jan_morning Properties of Modulus and Argument
If alpha denotes the number of solutions of |1 - i|^x = 2^x and beta = left(frac|z|arg(z)right), where z = fracpi4 (1 + i)^4 left(frac1 - sqrtpi isqrtpi + i + fracsqrtpi - i1 + sqrtpi iright), i = sqrt-1, then the distance of the point (alpha, beta) from the line 4x - 3y = 7 is
Numerical Answer. Answer: 3 to 3

Solution

### Core Logic |1 - i|^x = 2^x implies (sqrt2)^x = 2^x implies 2^x/2 = 2^x This implies fracx2 = x implies x = 0. There is exactly 1 solution, so alpha = 1. ### Step 1: Simplify complex number z (1+i)^4 = ((1+i)^2)^2 = (1 + i^2 + 2i)^2 = (2i)^2 = -4 Thus, z = -pi left( frac(1-sqrtpii)(sqrtpi-i)pi + 1 + frac(sqrtpi-i)(1-sqrtpii)1 + pi right) ### Step 2: Simplify Bracket Let's expand the terms directly: z = fracpi4(-4) left[ fracsqrtpi - pi i - i - sqrtpipi + 1 + fracsqrtpi - i - pi i - sqrtpi1 + pi right] = -pi left[ frac-i(pi+1)pi+1 + frac-i(pi+1)pi+1 right] = -pi [ -i - i ] = 2pi i ### Step 3: Find beta For z = 2pi i: |z| = 2pi and arg(z) = fracpi2. beta = frac|z|arg(z) = frac2pipi/2 = 4 ### Step 4: Distance from Line Distance of point (alpha, beta) = (1, 4) from the line 4x - 3y - 7 = 0: D = frac|4(1) - 3(4) - 7|sqrt4^2 + (-3)^2 = frac|4 - 12 - 7|5 = frac|-15|5 = 3 ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Maths: Complex Numbers and Quadratic Equations Class 11 Maths: Straight Lines
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