@ Isa
h(x) + g(x) - f(x)
h(x)= x^5 - 2x^4 - 2x^3 - x -3
+
g(x)= -x^5 + 2x^4 - 3x^3 - x^2 - 2x - 7
+
-f(x) = - 2x^5+4x^4 -3x^3+x^2 -5x +1
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h(x) + g(x) - f(x) = -2 x^5 +4x^4 -8x^3 -8x -9
* h(x) - g(x) + f(x)
h(x)= x^5 - 2x^4 - 2x^3 - x -3
+
- g(x)= x^5 -2x^4 +3x^3 +x^2 + 2x +7
+
f(x) = 2x^5 - 4x^4 + 3x^3 - x^2 + 5x-1
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h(x) - g(x) + f(x) = 2x^5 -8x^4 +4 x^3 +6x +3