是这样的吗?记x+2=t,（x+1)^4+(x+3)^4-272=(t-1)^4+(t+1)^4-272=2t^4+12t^2-270=2(t^2-9)(t^2+15)=2(t-3)(t+3)(t^2+15)=2(x-1)(x+5)(x^2+4x+19).参考以下的做法：（x+1）^4+(x+3)^4-272 =(x+3)^4-4^4+(x+1)^4-2^4 （...(t-1)^4+(t+1)^4-272是怎么到下面一步的？(t-1)^4=[(t-1)^2]^2=(t^2-2t+1)^2=t^4+4t^2+1-4t^3+2t^2-4t

(t+1)^4=(t^2+2t+1)^2=t^4+4t^2+1+4t^3+2t^2+4t
故有(t-1)^4+(t+1)^4=2t^4+12t^2+2