解
3ax²+6axy+3ay²
=3a(x²+2xy+y²)
=3a(x+y)²
4a的4次方-64
=4(a^4-16)
=4(a²-4)(a²+4)
=4(a-2)(a+2)(a²+4)
x^4-18x²y²+81y^4
=(x²-9y²)²
=(x-3y)²(x+3y)²
(x²-y)²-(1-y)²
=(x²-y-1+y)(x²-y+1-y)
=(x²-1)(x²-2y+1)
=(x-1)(x+1)(y-1)²