Question 821250
20x^4 +  154x^3 +  40x^2 - 418x - 84 = 0
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10x^4 + 77x^3 + 20x^2 - 209x - 42 = 0
(2x-3)(5x+1)(x+2)(x+7) = 0
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x = 3/2 or x = -1/5 or x = -2 or x = -7
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You might search Google for a general method for solving
quartic equations.
I find the easiest way is to graph them and find the 
graph's intersection with the x-axis. That reveals the
roots.
You could also use Newton's method for approximating
Real roots.
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Cheers,
Stan H.
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