Question

is 2/3 a complex number?

Answer 1

Is this a test?

Answer 2

http://en.wikipedia.org/wiki/Number

Answer 3

Are there any imaginary numbers, then........

Answer 4

its complex

Answer 5

any number is complex

Answer 6

2/3 +0*i

Answer 7

any number is complex?

Answer 8

Depends on which math class you are in.


For elementary algebra classes, this is a real number (since complex is yet to be introduced). The number is complex in this context if it has an imaginary part to it.


Note: overall, this number is complex since it's of the form a+bi where a=2/3 and b=0, but I get the feeling that the teacher is aiming for the first definition

Answer 9

it's complex

Answer 10

To be honest, the terminology is a bit strange when you encounter it. So teachers should address this issue a little better.

Answer 11

it is not imaginary ... but is complex

Answer 12

any number is complex
it is in the form a+bi where a and b are real

so 2/3=2/3+0*i
0 is a real number
so 2/3 is like totally complex

Answer 13

Let's just settle for rational....

Answer 14

there should not be several definitions for complex
all sets of numbers are subsets of the complex

Answer 15

But when you don't know about complex numbers, everything is real (or it's not real). If something is "real" in an elementary algebra class, then it's just any old number


But if some number is not real, then it's considered to be complex


ex: the number 2 is real, but 2+i is complex. In an elementary algebra class, 2 would NOT be considered complex (even though it really is)

Answer 16

it should be considered complex since it is

Answer 17

i guess what they mean is the best description

Answer 18

but if they don't know anything about complex numbers, then why is the teacher asking about complex numbers?

Answer 19

my guess is that they were introduced to them halfway through

Answer 20

thats a horrible thing to do
it sounds like a way to confuse the students

Answer 21

tell me about it, this is probably why many students hate algebra

Answer 22

algebra rocks!

Answer 23

they are specifically asking if it is a complex number...the only answer is yes

Answer 24

i totally agree with zarkon
but it seems wolfram is not on our side

Answer 25

Could be the op is asking on their own account...

Answer 26

http://www.wolframalpha.com/input/?i=2%2F3+is+complex%3F

Answer 27

but I've seen plenty of problems ask people to determine the nature of the roots

For instance, the equation x^2+4x+4=0 clearly has 2 real roots. But would you say that it also has complex roots? Sure the root itself (2) is complex, but an elementary algebra teacher would say that this root is real (a real double root actually)

Answer 28

and yes even wolfram even says it's not complex, so it's probably thinking along the same lines of reasoning as elementary algebra teachers

Answer 29

Negative then complex just came from a desire to have answers for every polynomial

Answer 30

\[\mathbb{R}\subset \mathbb{C}\]

every real number is complex

Answer 31

i don't get why wolfram says its not complex.

i think they say if you have b^2-4ac>0 gives you two real roots instead of saying two complex is because they are trying to narrow your set of numbers down

Answer 32

it's looking for the imaginary part, since it's not finding it, it's saying it's not complex

Answer 33

I suppose there is no reason to call it complex unless there is a reason to...

Answer 34

wolfram is incorrect in this case

Answer 35

i don't like that

Answer 36

wolfram is evil and cannot be trusted

Answer 37

lol

Answer 38

even though it's used constantly

Answer 39

How to confuse Wolfram

http://www.wolframalpha.com/input/?i=plot+x%3D2%2F3%2C+x%3D+2%2F3+%2B+0i

Answer 40

Links are busted..

Answer 41

From wolfram:"The complex numbers are the field C of numbers of the form x+iy, \
where x and y are real numbers and i is the imaginary unit equal to \
the square root of -1, sqrt(-1)."

looks like they are not using their own definition

Answer 42

Next time they ask me for an interval I'm gonna put C

Answer 43

Who needs R, lol