$A=x^4-7x^3+12x^2-x-3_{}$
$=x^4-2x^3-5x^3-x^2+10x^2+3x^2+5x-6x-3_{}$
$=x^2.(x^2-2x-1)-5x.(x^2-2x-1)+3.(x^2-2x-1)_{}$
$=(x^2-2x-1)(x^2-5x-3)_{}$
$B=x^5+3x^4-x^3-x^2+13x+5_{}$
$=x^5+3x^4+x^3-2x^3-6x^2+5x^2-2x+15x+5_{}$
$=x^3.(x^2+3x+1)-2x.(x^2+3x+1)+5.(x^2+3x+1)_{}$
$=(x^2+3x+1)(x^3-2x+5)_{}$
$Good_{}$ $luck_{}$