题目是否有错?
(x+1)(x+3)(x+5)(x+7)+16=(x+1)(x+7)(x+3)(x+5)+16
=（x^2+8x+7)(x^2+8x+15)+16
=(x^2+8x)^2+22*(x^2+8x)+105+16
=(x^2+8x)^2+22*(x^2+8x)+11^2
=（x^2+8x+11）^2