(color(red)(x)-color(blue)(4))(x^2+3x+2)
color(white)("XXX")= color(red)(x)(x^2+3x+2) - color(blue)(4)(x^2+3x+2)
color(white)("XXX")=(color(red)(x^3+3x^2+2x))-(color(blue)(4x^2+14x+8))
color(white)("XXX")=(color(red)(x^3)) +(color(red)3x^2-color(blue)(4x^2))+(color(red)(2x)-color(blue)(12x))+(color(blue)(-8))
color(white)("XXX")= x^3-x^2-10x-8