8（x²-2y²）-x（7x+y）+xy
=8x²-16y²-7x²-xy+xy
=x²-16y²
=(x+4y)(x-4y)
4a四次方-64
=4(a^4-16)
=4(a²+4)(a²-4)
=4(a²+4)(a+2)(a-2)
（5m²+3n²）²-（3m²+5n²）²
=[(5m²+3n²)+(3m²+5n²)][(5m²+3n²)-(3m²+5n²)]
=(8m²+8n²)(2m²-2n²)
=16(m²+n²)(m+n)(m-n)
x³+x²y-xy²-y³
=x²(x+y)-y²(x+y)
=(x+y)(x²-y²)
=(x+y)²(x-y)