原式=(x的4次方乘y的4次方+1)(x的4次方乘y的4次方-1)=(x的4次方乘y的4次方+1)(x²y²+1)(x²y²-1)=(x的4次方乘y的4次方+1)(x²y²+1)(xy+1)(xy-1)
(x^4y^4+1)（x^2y^2+1)(xy+1)(xy-1)
