Solving Complex Numbers Homework Statement

In summary, the conversation is about a math problem involving complex numbers. The speaker is struggling to solve the problem and needs help. They mention using the term "j" instead of "i" in complex numbers due to their field of study. They also mention attempting to eliminate the complex term in the denominator to make the problem easier to solve.
  • #1
Mathn00b
3
0

Homework Statement


Hi there, you can see from my nickname that I am a noob in maths :D.
So, here should is one problem that I cannot solve, even though I know some basics of complex numbers. Its the 2nd problem from the revision exercises, so please be gentle :)


Homework Equations


Find x and y :
(jy/(jx-1)-((3y+4j)/(3x+y)))=0
x = +-3/2 y = +-2
which probably means that at the end I have to end up with x^2 and y^2;
I am using j, since I am studying Electronics and in our math course we use j instead of i.


The Attempt at a Solution


I know that when we have j/i in the denominator, we have to multiply by its conjugate. I tried that and I don't seem to find the right answers.
Tried to eliminate the denominator like normal equation but it gets nastier and I am not even close to the solution.
Thanks
 
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  • #2
I assume you are given that x and y are real. That means getting rid of the complex term in the denominators (only one such in this case) will be useful, since you can then write the real and imaginary parts in separate equations. So please post your attempt at this.
 
  • #3
clear denominators
$$\require{cancel}\frac{\jmath \, y}{\jmath \, x -1}-\frac{3y+4\jmath}{3x+y}=0\\
\frac{\jmath \, y}{\jmath \, x -1}(\jmath \, x -1)(3x+y)-\frac{3y+4\jmath}{3x+y}(\jmath \, x -1)(3x+y)=0(\jmath \, x -1)(3x+y)\\
\frac{\jmath \, y}{\cancel{\jmath \, x -1}}(\cancel{\jmath \, x -1})(3x+y)-\frac{3y+4\jmath}{\cancel{3x+y}}(\jmath \, x -1)\cancel{(3x+y)}=0(\jmath \, x -1)(3x+y)\\
(\jmath \, y)(3x+y)-(3y+4\jmath)(\jmath \, x -1)=0$$
 

What are complex numbers?

Complex numbers are numbers that contain both a real part and an imaginary part. They can be written in the form a + bi, where a and b are real numbers and i is the imaginary unit equal to the square root of -1.

How do you add and subtract complex numbers?

To add complex numbers, simply add the real parts and imaginary parts separately. For example, (3 + 2i) + (5 + 4i) = (3+5) + (2i+4i) = 8 + 6i. To subtract complex numbers, follow the same process but subtract the real and imaginary parts instead.

How do you multiply and divide complex numbers?

To multiply complex numbers, 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. To divide complex numbers, multiply the numerator and denominator by the complex conjugate of the denominator and then simplify.

What is the complex conjugate?

The complex conjugate of a complex number a + bi is a - bi. This means that the sign of the imaginary part is changed. The product of a complex number and its complex conjugate always results in a real number.

How can complex numbers be represented graphically?

Complex numbers can be represented on a two-dimensional plane called the complex plane. The real part is plotted on the x-axis and the imaginary part is plotted on the y-axis. The complex number a + bi would be represented as the point (a,b) on the complex plane.

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