SOLUTION: Rounded to the nearest tenth, find the root of x^3-5x^2-12x+60=0 that lies between 3 and 4. Express your answer as a decimal. Thanks for the help!

Algebra ->  Complex Numbers Imaginary Numbers Solvers and Lesson -> SOLUTION: Rounded to the nearest tenth, find the root of x^3-5x^2-12x+60=0 that lies between 3 and 4. Express your answer as a decimal. Thanks for the help!      Log On


   



Question 929777: Rounded to the nearest tenth, find the root of x^3-5x^2-12x+60=0 that lies between 3 and 4. Express your answer as a decimal.
Thanks for the help!

Answer by MathTherapy(10552) About Me  (Show Source):
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Rounded to the nearest tenth, find the root of x^3-5x^2-12x+60=0 that lies between 3 and 4. Express your answer as a decimal.
Thanks for the help!
Using the rational root theorem, it's discovered that 5 is a root of the equation.
Thus, x = 5, or x - 5 = 0. This means that x - 5 is a factor of the equation: x%5E3+-+5x%5E2+-+12x+%2B+60+=+0.
When this equation is divided by the factor, x - 5, its QUOTIENT is: x%5E2+-+12. Thus, the factors of
x%5E3+-+5x%5E2+-+12x+%2B+60+=+0 are: (x - 5) and x%5E2+-+12.
Factoring x%5E2+-+12 further, we see that 2 other roots of the equation are: 3.464101615 and - 3.464101615.
Thus, the root that lies between 3 and 4 is: 3.464101615 ≈ highlight_green%283.5%29 (to the nearest tenth).
You can do the check!!
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