Solving equation with negative exponents

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To solve the equation 2x^(-1/3) - 9x^(-1/6) = -10, factoring out x^(-1/6) is a valid approach, leading to x^(-1/6)(2x - 9) = -10. Converting to fractions gives the equation as 2/x^(1/3) - 9/x^(1/6) = -10, which can be simplified by finding a common denominator. Recognizing that x^(1/3) can be expressed as (x^(1/6))^2 allows for a transformation into a quadratic form. Using substitutions can further simplify the equation for easier solving.
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Homework Statement



2x^(-1/3)-9x^(-1/6)= -10

Homework Equations



?

The Attempt at a Solution


I have tried to factor out x^(-1/6)
x^(-1/6) (2x-9)= -10
I'm not sure that's even right
I have also converted to fractions
1/2x^(1/3)-1/9x^(1/6)= -10
I'm not sure which route to go or if either is right?
 
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colts_R_best said:

Homework Statement



2x^(-1/3)-9x^(-1/6)= -10

Homework Equations



?

The Attempt at a Solution


I have tried to factor out x^(-1/6)
x^(-1/6) (2x-9)= -10
I'm not sure that's even right
I have also converted to fractions
1/2x^(1/3)-1/9x^(1/6)= -10
I'm not sure which route to go or if either is right?

If you write it this way, can you see what you can do to put the left hand side (LHS) over a common denominator in order to proceed?

\frac{2}{x^{1/3}} - \frac{9}{x^{1/6}} = -10
 
And as a further hint, x1/3 = (x1/6)2, so with the right substitution, your equation is quadratic in form.
 
Yeah always try to notice when you can turn an equation into a quadratic eg.

x + x^{-1} + A = 0 \Rightarrow x^2+1+Ax= 0


e^x + e^{-x} + A = 0 \Rightarrow (e^{x})^2 +1+ Ae^x = 0


\cot(x) + \tan(x) + A = 0 \Rightarrow 1 + \tan^2 x +A\tan x= 0 etc.

substitutions can be helpful aswell, like substitute e^x for y or something.
 
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
Since ##px^9+q## is the factor, then ##x^9=\frac{-q}{p}## will be one of the roots. Let ##f(x)=27x^{18}+bx^9+70##, then: $$27\left(\frac{-q}{p}\right)^2+b\left(\frac{-q}{p}\right)+70=0$$ $$b=27 \frac{q}{p}+70 \frac{p}{q}$$ $$b=\frac{27q^2+70p^2}{pq}$$ From this expression, it looks like there is no greatest value of ##b## because increasing the value of ##p## and ##q## will also increase the value of ##b##. How to find the greatest value of ##b##? Thanks
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