x＾4－3x＾3－5x＾2＋3x＋4
=(x^4-x^3)-(2x^3-2x^2)-(7x^2-7x)-(4x-4)
=x^3(x-1)-2x^2(x-1)-7x(x-1)-4(x-1)
=(x-1)(x^3-2x^2-7x-4)
=(x-1)[(x^3-2x^2-3x)-(4x+4)}
=(x-1)[x(x+1)(x-3)-4(x+1)]
=(x-1)(x+1)(x^2-3x-4)
=(x-1)(x-4)(x+1)^2