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Forcing a Polynomial Factor (Posted on 2013-08-03) |
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Find the values for a and b to force the polynomial x10 + ax5 + b to have x2+2x+3 as a factor.
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Submitted by Brian Smith
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Rating: 4.0000 (1 votes)
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Solution:
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x^10/(x^2+2x+3) has a remainder of 22x-219, then x^10-22x+219 has x^2+2x+3 as a factor.
x^5/(x^2+2x+3) has a remainder of -11x-12, then x^5+11x+12 has x^2+2x+3 as a factor.
Now to find a and b: the expression x^10-22x+219 + a(x^5+11x+12) must have the linear term drop out. a=2 does that. Then x^10-22x+219 + a(x^5+11x+12) = x^10 + 2x^5 + 243.
The answer is a=2, b=243. To check (x^10+2x^5+243)/(x^2+2x+3) = x^8-2x^7+x^6+4x^5-11x^4+12x^3+9x^2-54x+81. |
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