Is the Shaded Region Outside the Circle in the W Plane?

In summary, the conversation was about a problem involving finding the image of a complex function in the W-plane. The person was stuck on part b which involved shading regions inside or outside a circle, and was confused about whether the transformation into the W-plane affected this shading. The expert advised checking the positions of points with |z| < 3 and |z| > 3 in the W-plane to determine which region should be shaded.
  • #1
trew
19
0

Homework Statement


WeR5Bj4.png
[/B]

Homework Equations

The Attempt at a Solution



I had no problems with part a and was able to form the equation of the circle and get its centre/radius.

It's part b that I'm stuck on.

My notes show that for Z < 3 I would shade inside the circle but the mark scheme for this question is showing the circle but the region shaded is OUTSIDE the circle.

Does this have something to do with the transformation into the W plane?
 

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  • #2
Hello Trew, :welcome:

You can't write ##{\bf z} < 3## for a complex number ... :rolleyes: it's ##|{\bf z}| < 3## as in the problem description.
The latter is inside the circle in the ##\bf z ## plane -- as in your notes

But the exercise asks for the image (the complex 'range') of the function (transformation), so, as you suspect, in the ##\bf w## plane.
 
  • #3
BvU said:
Hello Trew, :welcome:

You can't write ##{\bf z} < 3## for a complex number ... :rolleyes: it's ##|{\bf z}| < 3## as in the problem description.
The latter is inside the circle in the ##\bf z ## plane -- as in your notes

But the exercise asks for the image (the complex 'range') of the function (transformation), so, as you suspect, in the ##\bf w## plane.

Hey BvU,

Appreciate the response and help.

So is it a case of it being the opposite if it is transformed into the W-plane?
 
  • #4
You say already found the circle in the W plane ? Check where a pont with ##|{\bf z}| < 3## ends up !
And double check with some points with ##|{\bf z}| > 3## !
 

What are complex numbers?

Complex numbers are numbers that contain both a real part and an imaginary part. They are usually written in the form a + bi, where a is the real part and bi is the imaginary part, and i is the imaginary unit.

How do you add or subtract complex numbers?

To add or subtract complex numbers, you simply add or subtract the real parts and the imaginary parts separately. For example, (3 + 2i) + (5 + 4i) = (3 + 5) + (2i + 4i) = 8 + 6i.

What is the conjugate of a complex number?

The conjugate of a complex number is a number with the same real part but the opposite sign of the imaginary part. For example, the conjugate of 3 + 2i is 3 - 2i.

How do you multiply complex numbers?

To multiply complex numbers, you use the FOIL method, just like you would with binomials. For example, (3 + 2i)(5 + 4i) = 15 + 12i + 10i + 8i^2 = 15 + 22i - 8 = 7 + 22i.

What is the modulus of a complex number?

The modulus of a complex number is the distance of the number from the origin on the complex plane. It is calculated by taking the square root of the sum of the squares of the real and imaginary parts. For example, the modulus of 3 + 4i is √(3^2 + 4^2) = √(9 + 16) = √25 = 5.

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