# Polynomials

• Dec 4th 2012, 12:25 PM
bob123
Polynomials
Hello all,

What would be the easiest way to simplify a polynomial raised to a fractional power. Such as this:

(40 + 2x)^(-2/3)

And here is the main problem:

I'm trying to solve for x in this equation:

821.6 = (40x)^(5/3) * (40 + 2x)^(-2/3)

All help is appreciated. Thank you.
• Dec 4th 2012, 12:53 PM
pickslides
Re: Polynomials
cubing both sides gives $\displaystyle 821.6^3 = (40x)^5\times (40+2x)^{-2}$

then getting rid of the negative exponent $\displaystyle 821.6^3\times (40+2x)^{2} = (40x)^5$

You should be good from there.
• Dec 4th 2012, 12:56 PM
coolge
Re: Polynomials
821.6 = { (40x)^5/(40+2x)^2}^(1/3)

raise both sides to the power of 3

821.6^3 = { (40x)^5/(40+2x)^2}

Now you can solve for x