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Skidibicutes1tg

$a)\left\lbrack\left(3x-2\right)\left(x+1\right)-\left(2x+5\right)\left(x^2-1\right)\right\rbrack:\left(x+1\right)$

$=\left(3x^2+x-2-2x^3-5x^2+2x+5\right):\left(x+1\right)$

$=\left(-2x^3-2x^2+3x+3\right):\left(x+1\right)$

$=\left(3-2x^2\right)\left(1+x\right):\left(x+1\right)$

$=3-2x^2$

$b)\left(2x+1\right)^2-2\left(2x+1\right)\left(3-x\right)+\left(3-x\right)^2$

$=4x^2+4x+1-2\left(-2x^2+5x+3\right)+x^2-6x+9$

$=5x^2-2x+10+4x^2-10x-6$

$=9x^2-12x+4$

$c)\left(x-1\right)^3-\left(x+1\right)\left(x^2-x+1\right)-\left(3x+1\right)\left(1-3x\right)$

$=x^3-3x^2+3x-1-x^3-1+9x^2-1$

$=6x^2+3x-3$.