=(a+1)^4+(a+3)^4-272
设出Y=a+1+a+3/2=a+2
原式=(y-1)4+(y+1)4-272
=2(y4+6y2+1)-272
=2(y4+6y2-135)
=2(y2-9)(y2+15)
=2(y+3)(y-3)(y2+15)
=2(x+5)(x-1)(x2+4x+19)