Converting to Polar and Cartesian form

AI Thread Summary
The discussion focuses on converting complex numbers to Cartesian and polar forms, specifically addressing the examples of -3-i/-8+6i and -2-2*sqrt(3i). Participants emphasize the importance of understanding the concepts of real and imaginary parts, as well as the modulus and argument of complex numbers. They suggest rationalizing the denominator when dealing with complex fractions and clarify that these numbers are indeed complex, not vector components. The conversation encourages the original poster to provide more details for better assistance.
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Okay I am totally confused in this.
This is not a homework question but rather one I saw online and was wondering for example how to solve it

The question was -3-i/-8+6i to be expressed into Cartesian form.

Another similar one was -2-2*sqrt(3i) into polar form.

How can I do this?

Can someone actually explain I don't get it fully. I know you usually use Cartesian form but yeah...
 
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Do you know what polar and cartesian forms are?
Do you know how to find the real and imaginary parts of a complex number?
Do you know how to find the modulus and argument of a complex number?
If the answer to any of the above is "no", then please look them up before returning.
If the answer to all of the above is "yes", then what's the problem?
Please show your best attempt.

Note:
1. search for: "rationalize the denominator"
2. search for: "square root of pi"
 
Are these complex numbers or vector components. When you have an i in the denominator, you may treat it as i^-1 which equals i which will help eliminating complex numbers. If it is a vector component, recall x=rcostheta y=rsintheta.
 
JohnPrior3 said:
Are these complex numbers or vector components.
It's fairly obvious that they are complex numbers.
JohnPrior3 said:
When you have an i in the denominator, you may treat it as i^-1 which equals i which will help eliminating complex numbers.
This doesn't help if the denominator has a sum of terms in it.
JohnPrior3 said:
If it is a vector component, recall x=rcostheta y=rsintheta.
 
you may treat it as i^-1 which equals i
... misplaced a minus sign I think, typo?
Just so people who google here don't get the wrong idea:$$\frac{1}{\sqrt{-1}}=\frac{1}{i}=-i$$ ... it's actually easier to use in the fraction form.

The trick: Since I can multiply by 1 without changing the number, and any number divided by itself is 1, I can do: $$\frac{1}{i} = \frac{i}{i}\frac{1}{i} = \frac{i}{-1} = -i$$ ... see what I did there?

The general form of this trick, when it leaves a real number in the denominator, is called "rationalizing the denominator" (see note post #2).
Hopefully OP will get back to us and supply the needed information.
 
I tried to combine those 2 formulas but it didn't work. I tried using another case where there are 2 red balls and 2 blue balls only so when combining the formula I got ##\frac{(4-1)!}{2!2!}=\frac{3}{2}## which does not make sense. Is there any formula to calculate cyclic permutation of identical objects or I have to do it by listing all the possibilities? Thanks
Since ##px^9+q## is the factor, then ##x^9=\frac{-q}{p}## will be one of the roots. Let ##f(x)=27x^{18}+bx^9+70##, then: $$27\left(\frac{-q}{p}\right)^2+b\left(\frac{-q}{p}\right)+70=0$$ $$b=27 \frac{q}{p}+70 \frac{p}{q}$$ $$b=\frac{27q^2+70p^2}{pq}$$ From this expression, it looks like there is no greatest value of ##b## because increasing the value of ##p## and ##q## will also increase the value of ##b##. How to find the greatest value of ##b##? Thanks
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