a) (x3 - x2 -5x -3) : (x-3)
= (x3 + x2 - 2x2 - 2x - 3x -3) : (x-3)
= [ x2(x+1) - 2x(x+1) -3(x+1)] : (x-3)
= (x+1).(x2 - 2x - 3) : (x-3)
= (x+1).(x2 - x - 3x - 3) : (x-3)
= (x+1). [x.(x+1) - 3(x+1)]
= (x+1).(x+1).(x-3) : (x-3)
= (x+1)2
= x2 + 2x 1
b) (x4 + x3 - 6x2 - 5x + 5 ) : (x2 + x -1)
= (x4 + x3 - x2 -5x2 -5x + 5) : (x2 + x -1)
= [ x2.(x2+x-1) - 5(x2+x-1)] :(x2 + x -1)
= (x2 + x -1).(x2 -5) : (x2 + x -1)
= x2 - 5