x+1)^4+(x+3)^4-272 =(x+1)^4+(x+3)^4-256-16 =(x+1)^4-16+(x+3)^4-256 =(x+1)^4-4^2+(x+3)^4-16^2 =[(x+1)^2+4][(x+1)^2-4]+[(x+3)^2+16][(x+3)^2-16] =[(x+1)^2+4]（x+1-2)(x+1+2)+[(x+3)^2+16](x+3-4)(x+3+4) =(x-1)[(x+1)^2+4](x+3)[(x+3)^2+16](x+7)