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Mathematics 15 Online
OpenStudy (anonymous):

Rationalizing the denominator?

OpenStudy (anonymous):

$$\frac{4 + \sqrt[3]{3}}{\sqrt[3]{6}}$$

OpenStudy (solomonzelman):

\[\huge\color{blue}{ \frac{(4+\sqrt[3]{6}) \times \sqrt[3]{6}}{\sqrt[3]{6} \times \sqrt[3]{6}} }\]

OpenStudy (anonymous):

The denominator would be: $$3 \sqrt[3]{2}$$ How do we we simplify further than that?

OpenStudy (solomonzelman):

No, it wouldn't be that. \[\huge\color{blue}{ \frac{4 \sqrt[3]{6}+6}{6} }.\]\[\huge\color{red}{ B/c~~both~~\sqrt[3]{6} \times \sqrt[3]{6}~~ became~6 }.\]

OpenStudy (solomonzelman):

Now divide top and bottom by 2.

OpenStudy (anonymous):

What property makes: $$\sqrt[3]{6} \times \sqrt[3]{6} = 6 ?$$

OpenStudy (solomonzelman):

My bad.\[\huge\color{blue}{ \frac{4+ \sqrt[3]{6}}{ \sqrt[3]{6} } }\]\[\huge\color{blue}{ \frac{(4+ \sqrt[3]{6}) \times \sqrt[3]{36}}{ \sqrt[3]{6}\times \sqrt[3]{36} } }\]

OpenStudy (solomonzelman):

because now it's going to be.\[\sqrt[3]{6^3}~~~~~~~~->~~~~~~~~6\]

OpenStudy (anonymous):

How did you get \(\sqrt[3]{36}\) ? I thought we multiply by the conjugate?

OpenStudy (solomonzelman):

I multiplied top and bottom times \[\sqrt[3]{36}\]

OpenStudy (anonymous):

Okay, so where did you get: \[\sqrt[3]{6^3}\]

OpenStudy (solomonzelman):

lets expand the parenthesis on top and bottom. \[\huge\color{blue}{ \frac{4\sqrt[3]{36}+6}{6} }~~~->~~~\huge\color{blue}{ \frac{2\sqrt[3]{36}+3}{3} }\] the reason I said \[\sqrt[3]{6^3}\] is because when I simplify the bottom, \[\sqrt[3]{6} \times \sqrt[3]{36}~~->~~\sqrt[3]{6} \times \sqrt[3]{6^2}~~->~~\sqrt[3]{6 \times 6^2}~~~->~~~\sqrt[3]{6^3}~~~->~~~6.\]

OpenStudy (anonymous):

Thank you :-).

OpenStudy (solomonzelman):

YW!

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