[(4分之1a+b)的平方+(4分之1a-b)的平方](8分之1a的平方-2b的平方)
=(1/16a²+1/2ab+b²+1/16a²-1/2ab+b²)(1/8a²-2b²)
=(1/8a²+2b²)(1/8a²-2b²)
=1/64a⁴-4b⁴