Выражения (x+2)*(3+x)*(3-x)+x^2(x+2)=? , (x+4)^2-9(x-4)^2=?

А)(х+2)(3+х)(3-х)+х^2(х+2)=(х+2)(9-х^2)+х^2(х+2)=(х+2)(9-х^2+х^2)=9(х+2)
б)(х+4)^2-9(х-4)^2=(х+4)^2-3^2(х-4)^2=((х+4)-3(х-4))((х+4)+3(х-4))=(х+4-3х+12)(х+4+3х-12)=(16-2х)(4х-8)=8(8-х)(х-2)