Simplifying with rational and negative exponents

AI Thread Summary
The discussion focuses on simplifying the expression 3(y)(1/3)-3x(y)(-2/3)(2x) / [(y)(1/3)]2. Participants confirm the correct interpretation of the expression and suggest separating the terms for easier simplification. The initial attempts at simplification are acknowledged as incorrect, with advice against converting to radicals prematurely. The conversation emphasizes the importance of correctly applying exponent rules and rationalizing the expression. Ultimately, separating the terms is recommended as a more effective approach to reach the solution.
scarne92
Messages
6
Reaction score
0

Homework Statement



Simplify the expression completely

3(y)(1/3)-3x(y)(-2/3)(2x) / [(y)(1/3)]2


The Attempt at a Solution



My attempt is totally wrong. I can't quit figure out what to do or where to start

3(y)(1/3)-3x(y)(-2/3)(2x) / [(y)(1/3)]2

3(y)(1/3)-6x(y)(-2/3) / y(2/3)

3√[3(y)(1/3)-6x(y)(-2/3) / y(2/3)]

3√(3) y - 3√(6x) y-2 / y2

3√(3) y - 3√(6x) / y4

3√3 - 3√6x / y3

(3√3 - 3√6x / y3)3

(3-6x) / y9
 
Physics news on Phys.org
scarne92 said:

Homework Statement



Simplify the expression completely

3(y)(1/3)-3x(y)(-2/3)(2x) / [(y)(1/3)]2
Although you have used lots of parentheses, for which you are to be applauded, you might be missing the most important pair.

It looks like this is the expression you need to simplify:
$$ \frac{3y^{1/3} - 3xy^{-2/3}2x}{y^{2/3}}$$
Or, without using LaTeX:
[3y1/3 - 3xy-2/32x]/y2/3

Please verify that this is your expression (or not).
scarne92 said:

The Attempt at a Solution



My attempt is totally wrong. I can't quit figure out what to do or where to start

3(y)(1/3)-3x(y)(-2/3)(2x) / [(y)(1/3)]2

3(y)(1/3)-6x(y)(-2/3) / y(2/3)

3√[3(y)(1/3)-6x(y)(-2/3) / y(2/3)]

3√(3) y - 3√(6x) y-2 / y2
It's not a good idea to convert to radicals at this point.
scarne92 said:
3√(3) y - 3√(6x) / y4

3√3 - 3√6x / y3

(3√3 - 3√6x / y3)3

(3-6x) / y9
 
$$ \frac{3y^{1/3} - 3xy^{-2/3}2x}{y^{2/3}}$$

yes that is the expression, I couldn't get the LaTex to work properly, but yes.
 
scarne92 said:
$$ \frac{3y^{1/3} - 3xy^{-2/3}2x}{y^{2/3}}$$

yes that is the expression, I couldn't get the LaTex to work properly, but yes.

looks like if you try separating them like this

$$\frac{3y^{1/3}}{y^{2/3}} - \frac{3xy^{-2/3}2x}{y^{2/3}}$$

it should work out a bit better
 
I tried to combine those 2 formulas but it didn't work. I tried using another case where there are 2 red balls and 2 blue balls only so when combining the formula I got ##\frac{(4-1)!}{2!2!}=\frac{3}{2}## which does not make sense. Is there any formula to calculate cyclic permutation of identical objects or I have to do it by listing all the possibilities? Thanks
Essentially I just have this problem that I'm stuck on, on a sheet about complex numbers: Show that, for ##|r|<1,## $$1+r\cos(x)+r^2\cos(2x)+r^3\cos(3x)...=\frac{1-r\cos(x)}{1-2r\cos(x)+r^2}$$ My first thought was to express it as a geometric series, where the real part of the sum of the series would be the series you see above: $$1+re^{ix}+r^2e^{2ix}+r^3e^{3ix}...$$ The sum of this series is just: $$\frac{(re^{ix})^n-1}{re^{ix} - 1}$$ I'm having some trouble trying to figure out what to...
Back
Top