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## #1 2012-07-29 20:12:59

debjit625
Member
Registered: 2012-07-23
Posts: 101

### Help with qudratic equation

Hi all I am having problem with this qudratic equation with signs ,or I am doing something silly ,its all about square root of complex number.

------Eq 1
------Eq 2
We can write Eq 2 as

Now we can write Eq 1 as

Is my last equation correct? (I hope so),if yes please solve it using qudratic formula ,as far you can
I have did it but my answer is not matching with correct answer got from other process.The sign is not matching but yes if I write the last equation like this

Thanks

Debjit Roy
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The essence of mathematics lies in its freedom - Georg Cantor

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## #2 2012-07-29 20:20:21

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

### Re: Help with qudratic equation

Hi debjit625

Try to substitute y^2=t when you get the quadratic. The solve for t and y will be just the plus/minus square root of 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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## #3 2012-07-29 20:26:24

debjit625
Member
Registered: 2012-07-23
Posts: 101

### Re: Help with qudratic equation

No you didnt got my problem ,I know that  I am solving for y^2,and after solving for y^2 I have to remove the square,The problem is different just solve it and I will tell it about...
Actually I am solving for this

Debjit Roy
___________________________________________________
The essence of mathematics lies in its freedom - Georg Cantor

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## #4 2012-07-29 20:34:44

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

### Re: Help with qudratic equation

Hi debjit625

Is this what you get?

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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## #5 2012-07-29 20:49:29

debjit625
Member
Registered: 2012-07-23
Posts: 101

### Re: Help with qudratic equation

Ok before you guys think too much let me tell you where I got this from...as I said its about square root fo a complex number
Let z be a complex number

and its square root be c

Then

So
--- Eq1
--- Eq 2

Now every where they (in books,resource,etc)  find x using quadratic formula, and after that they substitute x in Eq2 to find y.But what I am doing is I am trying to find y using quadratic formula ,but my signs(+/-) doesnt matches. I think its math and what process we take it doesnt matters ,the answer will be always same. I must be doing something very very silly...which is not coming into my mind right now but it will come later it always happens with me.

Debjit Roy
___________________________________________________
The essence of mathematics lies in its freedom - Georg Cantor

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## #6 2012-07-29 20:55:44

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

### Re: Help with qudratic equation

Hi debjit625

What do you get as the answer and what does the book get as the answer?

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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## #7 2012-07-29 20:56:29

debjit625
Member
Registered: 2012-07-23
Posts: 101

### Re: Help with qudratic equation

anonimnystefy yes what you got I also got that using that equation,but things changes when I use

Last edited by debjit625 (2012-07-29 20:58:11)

Debjit Roy
___________________________________________________
The essence of mathematics lies in its freedom - Georg Cantor

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## #8 2012-07-29 21:00:13

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

### Re: Help with qudratic equation

Hi debjit625

That is my solution with the plus/minus sign inside the root taken as +. I am sure taking the minus sign would work as well.

What did you say the correct solution should be?

Last edited by anonimnystefy (2012-07-29 21:01:51)

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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## #9 2012-07-29 21:24:15

debjit625
Member
Registered: 2012-07-23
Posts: 101

### Re: Help with qudratic equation

anonimnystefy  wrote:

That is my solution with the plus/minus sign inside the root taken as +. I am sure taking the minus sign would work as well.

No the minus will not work in this case , as we are finding y^2 and y^2 cant be negative.
But thats not the big problem of mine...my problem is that I can't get to the answer using this equation

And the correct answer for x and y in my book and every where else is

Another thing I want to say,when I write the equation

to this,i.e.. moving the equation from one side to another

I get correct answer.Is here I am doing something wrong?

Last edited by debjit625 (2012-07-29 21:27:52)

Debjit Roy
___________________________________________________
The essence of mathematics lies in its freedom - Georg Cantor

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## #10 2012-07-29 21:46:59

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

### Re: Help with qudratic equation

Moving everything shouldn't change anything.

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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## #11 2012-07-29 21:58:37

debjit625
Member
Registered: 2012-07-23
Posts: 101

### Re: Help with qudratic equation

Ok ,I was going to ask to you to show the steps but suddenly I realized that I have got it...
Actually I answered my question in post #9

Thanks for your time bro, "talking to you made my crazy mind to work"

Debjit Roy
___________________________________________________
The essence of mathematics lies in its freedom - Georg Cantor

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## #12 2012-07-29 22:35:23

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

### Re: Help with qudratic equation

You're welcome. But I am sure you are not crazy.

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.

Offline