Algebra II Simplifying Radicals Using Product and Quotient Properties

In summary, the original fraction of \sqrt[3]{\frac{5}{4}} can be simplified to \frac{\sqrt[3]{10}}{2} by changing the fraction to an equivalent form of \frac{\sqrt[3]{10}}{8} and taking the cube root of the numerator and denominator separately.
  • #1
velox_xox
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Homework Statement


Simplify. [itex]\sqrt[3]{\frac{5}{4}} [/itex]

The answer according to the textbook is: [itex]\frac{\sqrt [3]{10}}{2} [/itex]

Homework Equations


--


The Attempt at a Solution



Separated numerator and deonominator into individual cube roots and multiplied both by [itex]\sqrt[3] {4} [/itex].
[tex]\frac{\sqrt [3] {5}}{\sqrt [3] {4}}\cdot \frac {\sqrt [3] {4}}{\sqrt [3] {4}} [/tex]
Multiplied.
[tex] \frac {\sqrt [3] 20}{4} [/tex]

And that is as far as I've gotten. Did I do the process wrong? Because I do see that '20' and '4' could be simplified to '10' and '2' respectively, but not from the way I did it. I shall endeavor to not bend the rules of algebra to get the right answer, so what way should I have done it instead?

Also, if I could request the "tiniest" hints possible and then if I don't get it, increasingly larger hints; I would greatly appreciate it. (I'm trying my best to challenge myself to grasp the subject as much as I can on my own. And I do have people readily around me that are very good at math, but the problem is they just give the answer and process away without letting me earn it. That's why I'm here at PF.) So, please and thanks in advance!
 
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  • #2
...but [itex]\sqrt[3]{4}^2 \neq 4[/itex]
[tex]\sqrt[3]{4}=\sqrt[3]{2^2} = \sqrt[3]{2}^2 [/tex]
 
  • #3
Instead of multiplying by the cube root of 4 over itself, multiply by the cube root of 16 over itself.
 
  • #4
Or try changing the original fraction inside the cube root to an equivalent fraction, so that when you take the cube root of the numerator and denominator separately, you get [itex]\sqrt[3]{10}[/itex] in the numerator and [itex]2[/itex] in the denominator.

Hint : [itex]\sqrt[3]{2^{3}} [/itex]
 
  • #5
Or (pretty much the same) since [itex]4= 2^2[/itex], you need another "2" to get a perfect cube:
[tex]\sqrt[3]{\frac{5}{4}}= \sqrt[3]{\frac{5}{4}\frac{2}{2}}= \sqrt[3]{\frac{10}{8}}[/tex]
[tex]= \frac{\sqrt[3]{10}}{2}[/tex]
 
  • #6
... Wow. That should have been obvious to me; I was looking at a cube root as a square root. *sigh*

Thank you everyone for your help. I just now logged in and was able to decipher your hints very quickly. I tried it for myself, and it made sense. Sorry, that was an obvious one for everybody!

Thank you Joffan, Mark44, BloodyFrozen, and HallsofIvy. I appreciate your speedy and helpful replies!
 

1. How do I simplify a radical expression using the product property?

To simplify a radical expression using the product property, you need to multiply the numbers inside the radical together and simplify any perfect squares that result. For example, the expression √12 can be simplified to 2√3 because 12 is equal to 4 x 3, and 4 is a perfect square.

2. Can I use the product property to simplify a radical that has a variable inside?

Yes, you can use the product property to simplify radicals with variables. Simply multiply the coefficients and combine the variables inside the radical. For example, √18x can be simplified to 3√2x because 18 is equal to 9 x 2, and 9 is a perfect square.

3. How does the quotient property work in simplifying radicals?

The quotient property states that you can simplify a radical expression that has a fraction inside by taking the square root of the numerator and denominator separately. For example, √27/√9 can be simplified to 3 because the square root of 27 is 3 and the square root of 9 is 3.

4. What do I do if the radical has a number that is not a perfect square?

If the number inside the radical is not a perfect square, you can still simplify it by finding the largest perfect square that is a factor of the number and rewriting the radical as the square root of that perfect square multiplied by the remaining factors. For example, √48 can be simplified to 4√3 because 48 is equal to 16 x 3, and 16 is a perfect square.

5. Can I simplify a radical expression with more than one term using the product and quotient properties?

No, the product and quotient properties can only be applied to simplify radicals with a single term inside. If there are multiple terms, you can use other algebraic techniques such as factoring and combining like terms to simplify the expression further.

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