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December 16th, 2010, 07:03 AM   #1
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Domain !

find the domain
1\ root(4x^3-3x^2-x)
2\root(x^2+3x-4) root ( 2-x-x^2)
3\ root(x^2+3x-4)\root(x-2)^2
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December 16th, 2010, 07:16 AM   #2
ace
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Re: Domain !

Quote:
Originally Posted by ahmed-ar
find the domain
1\ root(4x^3-3x^2-x)
2\root(x^2+3x-4) root ( 2-x-x^2)
3\ root(x^2+3x-4)\root(x-2)^2
What's the condition for the function in the radical to be defined?
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December 16th, 2010, 07:24 AM   #3
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Re: Domain !

Quote:
Originally Posted by ace
Quote:
Originally Posted by ahmed-ar
find the domain
1\ root(4x^3-3x^2-x)
2\root(x^2+3x-4) root ( 2-x-x^2)
3\ root(x^2+3x-4)\root(x-2)^2
What's the condition for the function in the radical to be defined?
as i know x should be equal or bigger than 0 but i don't know how to find the domain!
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December 16th, 2010, 07:26 AM   #4
ace
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Re: Domain !

[quote=ahmed-ar]
Quote:
Originally Posted by ace
Quote:
Originally Posted by "ahmed-ar":26i3ji5f
find the domain
1\ root(4x^3-3x^2-x)
2\root(x^2+3x-4) root ( 2-x-x^2)
3\ root(x^2+3x-4)\root(x-2)^2
What's the condition for the function in the radical to be defined?
as i know x should be equal or bigger than 0 but i don't know how to find the domain![/quote:26i3ji5f]

Yes.

(1) 4x^3-3x^2-x>=0

Can you solve this? The solutions are the domain of this function. Do the same to the rest and take the intersection of the solutions.
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December 16th, 2010, 07:32 AM   #5
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Re: Domain !

i know how to solve but how to write the domain

i will find more then one answer of x
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December 16th, 2010, 07:41 AM   #6
ace
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Re: Domain !

Quote:
Originally Posted by ahmed-ar
i know how to solve but how to write the domain

i will find more then one answer of x
The same way you would write the solutions of an inequality.

If you were to write it in solution sets, {x: x>a or x<-b for x is all reals}. I am sure you can google this or refer to the examples in your textbook.
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December 16th, 2010, 07:56 AM   #7
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Re: Domain !

Quote:
Originally Posted by ace
Quote:
Originally Posted by ahmed-ar
i know how to solve but how to write the domain

i will find more then one answer of x
The same way you would write the solutions of an inequality.

If you were to write it in solution sets, {x: x>a or x<-b for x is all reals}. I am sure you can google this or refer to the examples in your textbook.
i haven't got it!
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December 16th, 2010, 08:00 AM   #8
ace
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Re: Domain !

[quote=ahmed-ar]
Quote:
Originally Posted by ace
Quote:
Originally Posted by "ahmed-ar":2bm9pdw7
i know how to solve but how to write the domain

i will find more then one answer of x
The same way you would write the solutions of an inequality.

If you were to write it in solution sets, {x: x>a or x<-b for x is all reals}. I am sure you can google this or refer to the examples in your textbook.
i haven't got it![/quote:2bm9pdw7]

Lets say the domain is x>3. You can write,

(1) The domain is (3 , infinity)

(2) The domain is x>3,

(3) {x>3 , }

These are the few ways of representing a domain. Is this what you are asking?
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December 16th, 2010, 08:14 AM   #9
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Re: Domain !

thanks

and what about if i got more than one value of x?
for example in first question i will get
x(4x+1)(x-1)>=0
so what will be the answer ?
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December 16th, 2010, 08:19 AM   #10
ace
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Re: Domain !

Quote:
Originally Posted by ahmed-ar
thanks

and what about if i got more than one value of x?
for example in first question i will get
x(4x+1)(x-1)>=0
so what will be the answer ?
It's simply the domain of the inequality. The way of writing it is the same.
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