(1)16（p+q)^2-9(p-q)^2
=[4(p+q)]²-[3(p-q)]²
=[4(p+q)+ 3(p-q)]×[4(p+q)-3(p-q)]
=(7p+q)(p+7q)
(2)m^5n^5-2n^3m^3+mn
=mn(m^4n^4-2n²m²+1)
=mn(m²n²-1)²
=mn(mn+1)²(mn-1)²