(x^2+10x+4)(x^2+10x-2)-55
=(x^2+10x)^2+2(x^2+10x)-63
=(x^2+10x+9)(x^2+10x-7)
=(x+1)(x+9)(x^2+10x+25-32)
=(x+1)(x+9)(x+5+4√2)（x+5-4√2）