a的4次方-2a的二次方b的二次方-8b的4次方
=(a²-4b²)(a²+2b²)
=(a+2b)(a-2b)(a²+2b²)
（x的二次方-3）的二次方+（x的二次方-3）-2
=(x²-3-1)(x²-3+2)
=(x²-4)(x²-1)
=(x+2)(x-2)(x+1)(x-1)