`(x-1)(x^3-3x-4)+(1-x)(x^3+3x+4)`

`=(1-x)(-x^3+3x+4+x^3+3x+4)`

`=(1-x)(6x+8)`

`=-6x^2-2x+8`

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`(2x^2-3x+1)(x^2-2)+(1-2x^2)(x^2+x+2)`

`=2x^4-3x^3-3x^2+6x-2-2x^4-2x^3-3x^2+x+2`

`=-5x^3-6x^2+7x`

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`(x-3)(x+2)+(x-4)(x+4)-(2x-1)x`

`=x^2-x-6+x^2-16-2x^2+x`

`=-22`

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`(x-2)(x^2+3x-5)-(5-x^2+x)(2-x)`

`=(x-2)(x^2+3x-5+5-x^2+x)`

`=4x(x-2)`

`=4x^2-8x`