How to Rationalize the Denominator of a Radical Expression?

  • Thread starter The legend
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In summary, the conversation discusses rationalizing the denominator of the expression \frac{1}{\sqrt[3]{a}+\sqrt[3]{b}+\sqrt[3]{c}} using algebraic equations. The attempt at a solution involves using the formula a^3 + b^3 + c^3 - 3abc = (a + b + c)(a^2 + b^2 + c^2 - ab - bc - ca) and then applying the formula x^3-y^3=(x-y)(x^2+xy+y^2). The conversation ends with a confirmation that the solution is correct.
  • #1
The legend
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Homework Statement


Rationalize the denominator..
[tex]
\frac{1}{\sqrt[3]{a}+\sqrt[3]{b}+\sqrt[3]{c}}
[/tex]


Homework Equations



Algebraic equations.

The Attempt at a Solution


So using the form
a3 + b3 + c3 - 3abc= (a + b + c)(a2 + b2 + c2 - ab - bc - ca)

So it becomes


[tex]
\frac{\sqrt[3]{a^2}+\sqrt[3]{b^2}+\sqrt[3]{c^2} -\sqrt[3]{ab}-\sqrt[3]{bc}-\sqrt[3]{ca} }{a + b + c - 3 \sqrt[3]{abc}}
[/tex]


Actually I don't know what to do next
If i try (a+b)(a-b) then it doesn't work out ...
 
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  • #2


Use

[tex]x^3-y^3=(x-y)(x^2+xy+y^2)[/tex]

ehild
 
  • #3


ehild said:
Use

[tex]x^3-y^3=(x-y)(x^2+xy+y^2)[/tex]

ehild
I don't see how this applies to the OP's problem.
 
  • #4


ehild said:
Use

[tex]x^3-y^3=(x-y)(x^2+xy+y^2)[/tex]

ehild

Mark44 said:
I don't see how this applies to the OP's problem.

[tex]x-y=\frac{x^3-y^3}{x^2+xy+y^2}[/tex]

:wink:
 
  • #6


Of course! An emoticon is worth a thousands words.

If there were a more suitable emoticon for "I'm sure you get it now" I would use that one instead.

:smile: << (don't kill me for this :-p)
 
  • #7


Yup got it!
Thanks!

(Checked it out with my teacher ... its right!)
 

FAQ: How to Rationalize the Denominator of a Radical Expression?

What does it mean to "rationalize the denominator"?

Rationalizing the denominator is a process of simplifying a fraction by removing any radicals or irrational numbers in the denominator. This makes the fraction easier to work with and understand.

Why is it important to rationalize the denominator?

Rationalizing the denominator is important because it allows us to perform operations on fractions more easily. It also helps us to compare and order fractions accurately.

How do you rationalize the denominator?

To rationalize the denominator, we multiply the numerator and denominator of the fraction by a suitable form of 1. This is usually done by multiplying by the conjugate of the denominator, which is the same expression with the sign between the terms changed.

Can you give an example of rationalizing the denominator?

Sure, let's take the fraction 3/√5. To rationalize the denominator, we multiply both the numerator and denominator by √5, giving us (3√5)/(√5√5). This simplifies to (3√5)/5, which is now in rationalized form.

When should you rationalize the denominator?

Rationalizing the denominator is typically done when working with fractions containing radicals or irrational numbers. It is especially useful when adding, subtracting, or comparing fractions, as it makes the process simpler and more accurate.

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