<span>2х(-х-3)^2-(x+1)(2-5x)(x-3)=2x(x^2+6x+9)-(2x+2-5x^2-5x)(x-3)=2x^3+12x^2+18x-(-5x^2-3x+2)(x-3)=2x^3+12x^2+18x-(-5x^3-3x^2+2x+15x^2+9x-6)=2x^3+12x^2+18x-(-5x^3+12x^2+11x-6)=2x^3+12x^2+18x+5x^3-12x^2-11x+6=7x^3+7x+6</span>
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