Change your subject.

bobbym · 2013-08-11 10:09:04

Sometimes you might call t =0 today for instance. You could run the equation back to t=-3. That would be 3 days ago. The variable can take negative values.

EbenezerSon · 2013-11-13 21:53:01

Is a member trying to indicate that a number in a principal square root must have only one answer?
For instance, if 9 is in a principal square root, must it have only one answer 3?

If I am getting him wrong please correct.

Thanks.

How do you do Bobbym?

EbenezerSon · 2013-11-13 22:15:40

The fellow's post is at #38.

What is the subtle difference between, a square root and a principal square root?

Thanks.

bobbym · 2013-11-14 03:45:11

Hi;

The unique nonnegative square root of a nonnegative real number. For example, the principal square root of 9 is 3, although both -3 and 3 are square roots of 9.

EbenezerSon · 2013-11-14 20:40:07

So if I am grasping it now, the principal square of a number produces only positive number.

Therefore, the principal square root always infers a positive number.
Am I right?

Please confirm.

EbenezerSon · 2013-11-14 20:49:49

Hi,

Please produce both the principal and the square root signs. So I will know thew properly

bobbym · 2013-11-14 20:50:48

Therefore, the principal square root always infers a positive number.

I would say yes.

http://www.mathsisfun.com/algebra/square-root.html

EbenezerSon · 2013-11-14 21:33:04

Hi,

I have browsed the link you provided, but couldn't distinguish the principal square root sign from the square root sign.

Some help.

anonimnystefy · 2013-11-14 21:39:03

The square root sign

is usually used to indicate the principle square root of a number.

bobbym · 2013-11-15 02:10:19

Hi;

Yep, that means positive root only.

EbenezerSon · 2013-11-15 02:38:34

Okay, what name do we give to a negative square root of a number? Since the positive root number has a name.

Thanks in advance.

bobbym · 2013-11-15 02:44:09

They are called complex or imaginary numbers.

EbenezerSon · 2013-11-15 02:55:59

Okay, finally finally.
If I am getting
the whole thing, The square root of 9 is 3 and -3.
the 3 is the prıncipal square root whereas the negative square root -3 is complex or imaginary square root, am I correct?
Please confirm.

bobbym · 2013-11-15 02:58:40

Both 3 and -3 when squared are 9. But only 3 is the principal square root.

√(-3) is complex or imaginary.

EbenezerSon · 2013-11-15 03:10:06

Please do you have an idea as to why it is called complex or imaginary?

bobbym · 2013-11-15 03:14:25

It was called imaginary because in the beginning when the concept of the root of a negative number was proposed most mathematicians did not like it. They called them imaginary numbers to sort of poke fun at the whole idea. Later, as it caught on, complex numbers was name given for them.

EbenezerSon · 2013-11-15 03:52:23

Thanks for that!

But when 9 is in a square root sign it gives two answers i.e -3 and 3.
if the positive number is the principal square root what name is also given to the -3?

bobbym · 2013-11-15 03:56:02

When 9 is in the square root sign that means principal square root, just the 3.

anonimnystefy · 2013-11-15 06:25:22

He is asking this:"If we call 3 the principal square root of 9, then what kind of square root of 9 is -3?". The answer is that there is no name given to it.

bobbym · 2013-11-15 06:34:17

We could say it is the root of the equation x^2 - 9 = 0.

anonimnystefy · 2013-11-15 06:36:30

We could, but, there is still no special name for non-principal roots.

bobbym · 2013-11-15 06:41:25

Everything you are saying is true but you are missing the point of my post #93 which essentially makes your post #94 non - essential.

anonimnystefy · 2013-11-15 06:55:46

Actually, #94 is me feeling you have not understood the question.

bobbym · 2013-11-15 06:57:57

Nope, I was dealing with a far more important concept and did not answer that question. Do you see it now?

anonimnystefy · 2013-11-15 13:54:31

But, what you said in #93 was already told and did not need repeating.

Math Is Fun Forum

#76 2013-08-11 10:09:04

Re: Change your subject.

#77 2013-11-13 21:53:01

Re: Change your subject.

#78 2013-11-13 22:15:40

Re: Change your subject.

#79 2013-11-14 03:45:11

Re: Change your subject.

#80 2013-11-14 20:40:07

Re: Change your subject.

#81 2013-11-14 20:49:49

Re: Change your subject.

#82 2013-11-14 20:50:48

Re: Change your subject.

#83 2013-11-14 21:33:04

Re: Change your subject.

#84 2013-11-14 21:39:03

Re: Change your subject.

#85 2013-11-15 02:10:19

Re: Change your subject.

#86 2013-11-15 02:38:34

Re: Change your subject.

#87 2013-11-15 02:44:09

Re: Change your subject.

#88 2013-11-15 02:55:59

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#89 2013-11-15 02:58:40

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