Electrical Engineering (EE) Exam  >  Electrical Engineering (EE) Questions  >  The function f(z) of complex variable z = x +... Start Learning for Free
The function f(z) of complex variable z = x + iy, where i = √−1, is given as f(z) = (x3 – 3xy2) + i v(x,y). For this function to be analytic, v(x,y) should be
  • a)
    (3xy2 – y3) + constant
  • b)
    (3x2y2 – y3) + constant
  • c)
    (x3 – 3x2y) + constant
  • d)
    (3x2y – y3) + constant
Correct answer is option 'D'. Can you explain this answer?
Most Upvoted Answer
The function f(z) of complex variable z = x + iy, where i = √&mi...
Understanding the Analytic Function
For a function f(z) = u(x,y) + iv(x,y) to be analytic, it must satisfy the Cauchy-Riemann equations. Here, u(x,y) = x^3 - 3xy^2, and we need to find v(x,y) that makes f(z) analytic.
Cauchy-Riemann Equations
The Cauchy-Riemann equations are given by:
- ∂u/∂x = ∂v/∂y
- ∂u/∂y = -∂v/∂x
Calculating partial derivatives of u:
- ∂u/∂x = 3x^2 - 3y^2
- ∂u/∂y = -6xy
Now, we can set up the equations:
From ∂u/∂x
- We have ∂v/∂y = 3x^2 - 3y^2.
From ∂u/∂y
- We have -∂v/∂x = -6xy, which implies ∂v/∂x = 6xy.
Finding v(x,y)
To find v(x,y), we integrate the equations:
1. Integrating ∂v/∂y = 3x^2 - 3y^2 gives:
- v(x,y) = (3x^2y - y^3) + C(x), where C(x) is an arbitrary function of x.
2. Next, we differentiate v with respect to x:
- ∂v/∂x = 6xy + C'(x).
Setting this equal to our earlier derived expression ∂v/∂x = 6xy, we find that C'(x) must be zero, meaning C(x) is a constant.
Conclusion
Thus, the function v(x,y) that satisfies the Cauchy-Riemann equations and makes f(z) analytic is:
v(x,y) = 3x^2y - y^3 + constant.
Therefore, the correct option is d) (3x^2y - y^3) + constant.
Free Test
Community Answer
The function f(z) of complex variable z = x + iy, where i = √&mi...
Concept:
f(z) = u + iv
u = real part
v = imaginary part
If f(z) is an analytic function

(This is an exact differential equation)
Calculation:
Given,
u = x3 – 3xy2
∂u/∂x = 3x2 − 3y2
∂u/∂y = −6xy

It is an exact differential equation the solution is obtained by treating y as constant in the first term and in the second term only that part is integrated which is not containing x.
Integrating the above equation
v = 3x2y − y+ constant
Explore Courses for Electrical Engineering (EE) exam

Top Courses for Electrical Engineering (EE)

The function f(z) of complex variable z = x + iy, where i = √−1, is given as f(z) = (x3 – 3xy2) + i v(x,y). For this function to be analytic, v(x,y) should bea)(3xy2 – y3) + constantb)(3x2y2 – y3) + constantc)(x3 – 3x2y) + constantd)(3x2y – y3) + constantCorrect answer is option 'D'. Can you explain this answer?
Question Description
The function f(z) of complex variable z = x + iy, where i = √−1, is given as f(z) = (x3 – 3xy2) + i v(x,y). For this function to be analytic, v(x,y) should bea)(3xy2 – y3) + constantb)(3x2y2 – y3) + constantc)(x3 – 3x2y) + constantd)(3x2y – y3) + constantCorrect answer is option 'D'. Can you explain this answer? for Electrical Engineering (EE) 2024 is part of Electrical Engineering (EE) preparation. The Question and answers have been prepared according to the Electrical Engineering (EE) exam syllabus. Information about The function f(z) of complex variable z = x + iy, where i = √−1, is given as f(z) = (x3 – 3xy2) + i v(x,y). For this function to be analytic, v(x,y) should bea)(3xy2 – y3) + constantb)(3x2y2 – y3) + constantc)(x3 – 3x2y) + constantd)(3x2y – y3) + constantCorrect answer is option 'D'. Can you explain this answer? covers all topics & solutions for Electrical Engineering (EE) 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for The function f(z) of complex variable z = x + iy, where i = √−1, is given as f(z) = (x3 – 3xy2) + i v(x,y). For this function to be analytic, v(x,y) should bea)(3xy2 – y3) + constantb)(3x2y2 – y3) + constantc)(x3 – 3x2y) + constantd)(3x2y – y3) + constantCorrect answer is option 'D'. Can you explain this answer?.
Solutions for The function f(z) of complex variable z = x + iy, where i = √−1, is given as f(z) = (x3 – 3xy2) + i v(x,y). For this function to be analytic, v(x,y) should bea)(3xy2 – y3) + constantb)(3x2y2 – y3) + constantc)(x3 – 3x2y) + constantd)(3x2y – y3) + constantCorrect answer is option 'D'. Can you explain this answer? in English & in Hindi are available as part of our courses for Electrical Engineering (EE). Download more important topics, notes, lectures and mock test series for Electrical Engineering (EE) Exam by signing up for free.
Here you can find the meaning of The function f(z) of complex variable z = x + iy, where i = √−1, is given as f(z) = (x3 – 3xy2) + i v(x,y). For this function to be analytic, v(x,y) should bea)(3xy2 – y3) + constantb)(3x2y2 – y3) + constantc)(x3 – 3x2y) + constantd)(3x2y – y3) + constantCorrect answer is option 'D'. Can you explain this answer? defined & explained in the simplest way possible. Besides giving the explanation of The function f(z) of complex variable z = x + iy, where i = √−1, is given as f(z) = (x3 – 3xy2) + i v(x,y). For this function to be analytic, v(x,y) should bea)(3xy2 – y3) + constantb)(3x2y2 – y3) + constantc)(x3 – 3x2y) + constantd)(3x2y – y3) + constantCorrect answer is option 'D'. Can you explain this answer?, a detailed solution for The function f(z) of complex variable z = x + iy, where i = √−1, is given as f(z) = (x3 – 3xy2) + i v(x,y). For this function to be analytic, v(x,y) should bea)(3xy2 – y3) + constantb)(3x2y2 – y3) + constantc)(x3 – 3x2y) + constantd)(3x2y – y3) + constantCorrect answer is option 'D'. Can you explain this answer? has been provided alongside types of The function f(z) of complex variable z = x + iy, where i = √−1, is given as f(z) = (x3 – 3xy2) + i v(x,y). For this function to be analytic, v(x,y) should bea)(3xy2 – y3) + constantb)(3x2y2 – y3) + constantc)(x3 – 3x2y) + constantd)(3x2y – y3) + constantCorrect answer is option 'D'. Can you explain this answer? theory, EduRev gives you an ample number of questions to practice The function f(z) of complex variable z = x + iy, where i = √−1, is given as f(z) = (x3 – 3xy2) + i v(x,y). For this function to be analytic, v(x,y) should bea)(3xy2 – y3) + constantb)(3x2y2 – y3) + constantc)(x3 – 3x2y) + constantd)(3x2y – y3) + constantCorrect answer is option 'D'. Can you explain this answer? tests, examples and also practice Electrical Engineering (EE) tests.
Explore Courses for Electrical Engineering (EE) exam

Top Courses for Electrical Engineering (EE)

Explore Courses
Signup for Free!
Signup to see your scores go up within 7 days! Learn & Practice with 1000+ FREE Notes, Videos & Tests.
10M+ students study on EduRev