`(x-10)^2-2(x-10)(5x-3)+(5x+3)`
`=x^2-20x+100-10x^2+106x-60+5x+3`
`=(x^2-10x^2)+(-20x+106x+5x)+(100-60+3)`
`=-9x^2+91x+43`
$\\$
`(x-2)^3-x(x-3)^2`
`=(x^3-6x^2+12x-8)-x(x^2-6x+9)`
`=x^3-6x^2+12x-8-x^3+6x^2-9x`
`=(x^3-x^3)+(6x^2-6x^2)+(12x-9x)-8`
`=3x-8`
$\\$
`(x-2)(x^2+2x+4)-x(x+1)(x-1)`
`=(x^3-8)-x(x^2-1)`
`=x^3-8-x^3+x`
`=(x^3-x^3)+x-8`
`=x-8`
$\\$
`(x+3)(x^2-3x+9)-x(x^2-1)`
`=x^3+27-x^3+x`
`=(x^3-x^3)+x+27`
`=x+27`