What the graph of (-2)^x is

  • Thread starter reaver
  • Start date
  • #1
reaver
Can some one tell me what the graph of (-2)^x is i tryed but i only got errors.

Thank in advance for your help

reaver
 
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Answers and Replies

  • #2
jonnylane
what do you mean by "what is the graph"?

just take some values of x, work out y with a calculator and draw it on some graph paper!

or write a few program lines..
 
  • #3
HallsofIvy
Science Advisor
Homework Helper
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I wonder if Jonnylane tried doing that himself! If you try to graph y= (-2)x by plotting values, you can calculate values for integer values of x but that won't necessarily tell you the true graph. In this case it certainly doesn't!

If you try to use a calculator to calculate values for fractional x, you are going to get more error messages.

In general, the function ax is only defined for positive a. (-2)x is going to be undefined for almost all x!
 
  • #4
3,077
4
Can the function be graphed in the complex plane, or is it truly undefined for nonintegral x values?
 
  • #5
ahrkron
Staff Emeritus
Gold Member
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You can obtain values of (-2)^x for any x, but your calculator needs a little help because you obtain complex values:

(-2)^x
= (2ei[pi])x
= 2x (ei[pi])x
= 2x (cos([pi]x) + i sin([pi]x))

Which is a spiral in the complex plane, which touches the real axis for all integer values of x.
 

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