What the graph of (-2)^x is

  • Thread starter reaver
  • Start date
  • #1

Main Question or Discussion Point

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

Last edited by a moderator:

Answers and Replies

  • #2
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
Science Advisor
Homework Helper
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
Can the function be graphed in the complex plane, or is it truly undefined for nonintegral x values?
  • #5
Staff Emeritus
Gold Member
You can obtain values of (-2)^x for any x, but your calculator needs a little help because you obtain complex values:

= (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.