SOLUTION: Hello, I would like to find help in HOW to solve a quadratic equation such as the one listed below. I am not quite sure on how to work the fractional powers. I have tried the quadr

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Question 1008619: Hello, I would like to find help in HOW to solve a quadratic equation such as the one listed below. I am not quite sure on how to work the fractional powers. I have tried the quadratic equation but that does not work out and I have tried seeing it as 9(x^(1/3))^2-26x^(1/3)-3=0. I have seen youtube videos on how to solve equations in quadratic with fractional powers but most factor nicely and I cannot seem to get my problem to do so as well. I would really appreciate some assistance with this problem.
9x^(2/3)-26x^(1/3)-3=0

Found 2 solutions by josgarithmetic, ikleyn:
Answer by josgarithmetic(39616)   (Show Source): You can put this solution on YOUR website!
Not a quadratic equation, but IN QUADRATIC FORM.

Pick some other variable, ...
arbitrarily choosing here, Let .

Re-express the equation as .
Continue from this.

Answer by ikleyn(52776)   (Show Source): You can put this solution on YOUR website!
.
9x^(2/3)-26x^(1/3)-3=0
---------------------------
The standard method solving equations like this is as follows.

Introduce new variable 

y = x^(1/3) =        (1).

Then your equation takes the form

 -  -  = .   (2)

It is a quadratic equation for y. Solve it using the quadratic formula:

 =  =  = .

Thus the equation (2) has two solutions:  = 3;    = .

Now, to find x, you need solve two equations ( recall (1) ):

1)  = 3. To solve it, raise both side to the degree 3: x =  = 27.

2)  = . To solve it, raise both side to the degree 3: x =  = .

Answer. There are two solutions of the original equation: x = 27 and x = .


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