Chapter 5:Indices and Logarithms @perl
\[(-\frac{ 3 }{ 8 })^{-\frac{ 2 }{ 3 }}\]
Find the value of the following.
because of the negative exponent you can flip the contents of the fraction
(-3/8)^(-2/3) = (-8/3)^(2/3)
okay
\[-\frac{ 8^{\frac{ 2 }{ 3 }} }{ 3^{\frac{ 2 }{ 3 }} }\]
yes
\[-\frac{ (2^3)^{\frac{ 2 }{ 3 }} }{ \sqrt[3]{3^2} }\]
\[-\frac{ 4 }{ \sqrt[3]{9} }\]
now you can rationalize denominator
How to rationalize denominator?
you have cube root of 3*3. if you have another cube root of 3 then you can rationalize denominator
a number is rationalized when u remove the square root, cube root,.... of it
\[-\frac{ 4 }{ 3\times3 }\] it's like this?
no
\(\Large -\frac{ 4 }{ \sqrt[3]{9} }=-\frac{ 4 }{ \sqrt[3]{9} }\times \frac{\sqrt[3]{9}}{ \sqrt[3]{9} }\\ \Large =-\frac{ 4 \sqrt[3]{9}}{9}\)
\[=\frac{ 4 }{ 9 }\]
i m feeling i made mistake
assuming we're interested only in real roots : \[\begin{align}\left(-\frac{ 3 }{ 8 }\right)^{-\frac{ 2 }{ 3 }} &= \left(-\frac{ 8 }{ 3 }\right)^{\frac{ 2 }{ 3 }}\\~\\ &= {\left[\left(-\frac{ 8 }{ 3 }\right)^2\right]}^{\frac{ 1 }{ 3 }}\\~\\ &= {\left[\frac{8^2}{3^2}\right]}^{\frac{ 1 }{ 3 }}\\~\\ &= {\left[\frac{(2^3)^2}{3^2}\right]}^{\frac{ 1 }{ 3 }}\\~\\ &= {\left[\frac{2^6}{3^2}\right]}^{\frac{ 1 }{ 3 }}\\~\\ &= {\left[\frac{2^6\times 3}{3^2\times 3}\right]}^{\frac{ 1 }{ 3 }}\\~\\ &= {\left[\frac{2^6\times 3}{3^3}\right]}^{\frac{ 1 }{ 3 }}\\~\\ &= \frac{(2^6\times 3)^{\frac{1}{3}}}{(3^3)^{\frac{1}{3}}}\\~\\ &=\frac{(2^6)^{\frac{1}{3}}3^{\frac{1}{3}}}{3}\\~\\ &=\frac{2^2\sqrt[3]{3}}{3}\\~\\ &= \frac{4\sqrt[3]{3}}{3} \end{align}\]
The answer in the book say it's 4/9.
lets ask wolfram http://www.wolframalpha.com/input/?i=simplify+%28-%5Cfrac%7B+3+%7D%7B+8+%7D%29%5E%7B-%5Cfrac%7B+2%7D%7B+3+%7D%7D
hmm
i agree o ganesh
i cant see any trick over there :O
like is it only dealing with reals or what :O
Thnx @ganeshie8 @perl @mathmath333 @ikram002p
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