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

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

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.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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

EbenezerSon
Member
Registered: 2013-07-04
Posts: 551

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?

I know only one thing - that is that I know nothing

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

EbenezerSon
Member
Registered: 2013-07-04
Posts: 551

The fellow's post is at #38.

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

Thanks.

I know only one thing - that is that I know nothing

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

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

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.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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

EbenezerSon
Member
Registered: 2013-07-04
Posts: 551

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?

I know only one thing - that is that I know nothing

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

EbenezerSon
Member
Registered: 2013-07-04
Posts: 551

Hi,

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

I know only one thing - that is that I know nothing

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

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

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

I would say yes.

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

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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

EbenezerSon
Member
Registered: 2013-07-04
Posts: 551

Hi,

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

Some help.

I know only one thing - that is that I know nothing

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

anonimnystefy
Real Member
From: Harlan's World
Registered: 2011-05-23
Posts: 16,037

The square root sign

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

Here lies the reader who will never open this book. He is forever dead.
Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

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

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Hi;

Yep, that means positive root only.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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

EbenezerSon
Member
Registered: 2013-07-04
Posts: 551

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

I know only one thing - that is that I know nothing

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

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

They are called complex or imaginary numbers.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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

EbenezerSon
Member
Registered: 2013-07-04
Posts: 551

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?

I know only one thing - that is that I know nothing

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

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

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

√(-3) is complex or imaginary.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #90 2013-11-15 03:10:06

EbenezerSon
Member
Registered: 2013-07-04
Posts: 551

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

I know only one thing - that is that I know nothing

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## #91 2013-11-15 03:14:25

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

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.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #92 2013-11-15 03:52:23

EbenezerSon
Member
Registered: 2013-07-04
Posts: 551

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?

I know only one thing - that is that I know nothing

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## #93 2013-11-15 03:56:02

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

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

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #94 2013-11-15 06:25:22

anonimnystefy
Real Member
From: Harlan's World
Registered: 2011-05-23
Posts: 16,037

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.

Here lies the reader who will never open this book. He is forever dead.
Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

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## #95 2013-11-15 06:34:17

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

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

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #96 2013-11-15 06:36:30

anonimnystefy
Real Member
From: Harlan's World
Registered: 2011-05-23
Posts: 16,037

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

Here lies the reader who will never open this book. He is forever dead.
Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

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## #97 2013-11-15 06:41:25

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

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

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #98 2013-11-15 06:55:46

anonimnystefy
Real Member
From: Harlan's World
Registered: 2011-05-23
Posts: 16,037

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

Here lies the reader who will never open this book. He is forever dead.
Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

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## #99 2013-11-15 06:57:57

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

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

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #100 2013-11-15 13:54:31

anonimnystefy
Real Member
From: Harlan's World
Registered: 2011-05-23
Posts: 16,037