Multiplicity 2 means you're using that same root twice. So we will FOIL out (x+1)(x+1)(x-3). Doing that multiplying gives us [tex]x^3+2x^2+x-3x^2-6x-3[/tex]. Combining like terms gives us the third degree polynomial we are looking for: [tex]x^3-x^2-5x-3[/tex]
