Question

Sum of (4x^4-x2-x)+(x^4+x^3+x^2+x-1)

Answer 1

                -9x4 + 5x2 - 26x - 12
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                                3

Answer 2

(4x^4-x2-x)+(x^4+x^3+x^2+x-1)
=4x^4 - x2 - x + x^4 + x^3 + x^2 +  x- 1
=5x^4 + x^3 - 1

(x^2 and x are canceled out)...
x^2 - x^2 = 0
x -x =0