Ta có: \(2x\left(3x^3-x\right)-4x^2\left(x-x^2+1\right)+\left(x-3x^2\right)x\)
=\(6x^4-2x^2-4x^3+4x^4-4x^2+x^2-3x^3\)
=\(10x^4-7x^3-5x^2\)
2x.3x3-2x.x-4x2.x-4x2.(-x2)-4x2.1+x.x-3x2.x
6x4-2x2-4x3+4x4-4x2+x2-3x3
(6x4+4x4)+(-4x3-3x3)+(-2x2-4x2+x2)
10x4-7x3-5x2
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