Solve: 27x^3 - 125 = 0

jhawk555

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Sep 26, 2006
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I am reviewing a test that I took. I got part of the answer correct and I am trying to understand how to do the second part correctly.

Solve: 27x^3 - 125 = 0

I started by factoring:

(3x - 5)(9x^2 + 15x + 25) = 0

3x - 5 = 0

3x = 5

x = 5/3

I am stuck with the second half of the equation as to where to start.
 
ever used the quadratic formula?

a = 9, b = 15, c = 25

fyi, the roots of this quadratic will be imaginary.
 
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