Troubleshooting: (-i)^4 Calculation Error on TI-36X Pro Calculator

In summary, the conversation discusses why a TI-36X Pro calculator returns a "Domain Error" when calculating (-i)^4, while it works fine on a TI-83 Plus. The possibility of the calculator using logs to calculate the value is mentioned, as well as the manual stating that it cannot compute i to a power greater than 3. It is suggested to consult the user manual or the company's website for more information.
  • #1
moouers
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I'm curious if anyone knows why my calculator would return "Domain Error" when calculating (-i)^4 on my TI-36X Pro?

((-i)^2)^2 works just fine on the machine, and (-i)^4 works just fine on my TI-83 Plus.

Any ideas?
 
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  • #2
moouers said:
I'm curious if anyone knows why my calculator would return "Domain Error" when calculating (-i)^4 on my TI-36X Pro?

((-i)^2)^2 works just fine on the machine, and (-i)^4 works just fine on my TI-83 Plus.

Any ideas?
The only thing I can think of is that the calculator might be using logs to calculate the value. The following is an identity for real x > 0.

xn = (eln(x))4 = e4ln(x).

It's possible that it is programmed to be able to calculate i2 and (-i)2, but for other powers it uses a different algorithm

Consult your user manual - it might have some information about the domains of the functions it can calculate. I'm sur they have a web site, and they might have a site where you can ask questions about the specific models.
 
  • #3
Thank you, Mark. I apologize for not recognizing your post sooner! I checked my user manual and it only says that it cannot compute i to a power greater than 3.
 

What does (-i)^4 equal to?

The expression (-i)^4 means (-i)(-i)(-i)(-i) which simplifies to 1. This is because when we multiply two complex numbers with the same argument, the result is a real number equal to the product of their magnitudes.

Why is there a domain error when (-i)^4 is evaluated?

The domain error occurs because the expression (-i)^4 is not defined in the complex number system. When we raise a complex number to a power, we use De Moivre's theorem which only applies to numbers with a non-negative real part. Since (-i) has a negative real part, we cannot use De Moivre's theorem and thus get a domain error.

Can (-i)^4 be expressed in terms of real numbers?

Yes, (-i)^4 equals to 1 which is a real number. This is because when we raise a complex number to the fourth power, the result is always a real number.

What is the geometric interpretation of (-i)^4?

The geometric interpretation of (-i)^4 is a rotation of 360 degrees (or 0 degrees) around the origin in the complex plane. This is because when we raise a complex number to the fourth power, we essentially multiply its argument by 4.

How can we evaluate (-i)^4 without getting a domain error?

To evaluate (-i)^4 without getting a domain error, we can use the polar form of complex numbers. We can rewrite (-i) as 1(cos(270) + isin(270)) and then apply De Moivre's theorem to raise it to the fourth power. This will result in 1(cos(1080) + isin(1080)) which simplifies to 1. Therefore, (-i)^4 equals to 1 without getting a domain error.

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