SOLUTION: Use synthetic division and the solution x=8-squareroot of 6 to find the seroes of x^3-8x^2-70x+464=0

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Question 269215: Use synthetic division and the solution
x=8-squareroot of 6
to find the seroes of
x^3-8x^2-70x+464=0

Answer by AnlytcPhil(1806) About Me  (Show Source):
You can put this solution on YOUR website!
Use synthetic division and the solution
x=8-sqrt%286%29
to find the seroes of
x%5E3-8x%5E2-70x%2B464=0


Do it the same way as you do any synthetic division.
You just have to spread it out more so thet there is
room for the square roots, and you will have to do
some of the multiplications out to the side or on
scratch paper.

 8-Ö6|1  -8     -70       464
     |    8-Ö6    6-8Ö6  -464
      1    -Ö6  -64-8Ö6     0

We got a zero remainder, so that means that 8-sqrt%286%29
is a solution.

That means we have factored  

x%5E3-8x%5E2-70x%2B464=0

as



Now since all the coefficients are integers, the conjugate of 
that, 8%2Bsqrt%286%29 is also a solution.  So we do another
synthetic division using the second parentheses and the
conjugate 8%2Bsqrt%286%29:



   8+Ö6|1   -Ö6  -64-8Ö6
       |   8+Ö6   64+8Ö6
        1  8           0  

Now we have finally factored the polynomial this way:

%28x-%0D%0A%0D%0A%288-sqrt%286%29%29%29+%2A+%28x-%288%2Bsqrt%286%29%29%29+%2A%28x%2B8%29=0+

Set those three factors equal to 0 and you get the three
solutions:

x=8-sqrt%286%29, x=8%2Bsqrt%286%29, x=-8

Edwin