Drexel dragonThe Math ForumDonate to the Math Forum

Ask Dr. Math - Questions and Answers from our Archives
_____________________________________________
Associated Topics || Dr. Math Home || Search Dr. Math
_____________________________________________

Square Roots, Complex Numbers


Date: Sat, 15 Jun 1996 00:03:07 -0400 (EDT) 
From: Anonymous
Subject: Square Roots

x^2 = -9

I tried taking the square root of both sides. Is this impossible?


Date: Sat, 15 Jun 1996 09:25:18 -0400 (EDT) 
From: Dr. Ethan
Subject: Re: Square Roots

Hello,

It depends on what you mean by impossible. If you want the answer 
to be a real number like ones you are used to (like 2, 3.769, 
17.55555.. , Pi, etc.) then it is impossible, but mathematicians have 
come up with a whole area of mathematics and a whole system of 
numbers that has no problem with x^2 = -9. They are called 
complex numbers. 

They use the symbol i to denote the square root of -1 so in your 
problem, x = 3i. 

If you would like more information on complex numbers, write 
back and ask.

-Doctor Ethan, The Math Forum
    
Associated Topics:
High School Imaginary/Complex Numbers
High School Square & Cube Roots
Middle School Square Roots

Search the Dr. Math Library:


Find items containing (put spaces between keywords):
 
Click only once for faster results:

[ Choose "whole words" when searching for a word like age.]

all keywords, in any order at least one, that exact phrase
parts of words whole words

Submit your own question to Dr. Math

[Privacy Policy] [Terms of Use]

_____________________________________
Math Forum Home || Math Library || Quick Reference || Math Forum Search
_____________________________________

Ask Dr. MathTM
© 1994-2013 The Math Forum
http://mathforum.org/dr.math/