1.原式=-(8a³b²-12ab³c+6a²b) =-2ab(4a²b-6b²c+3a)2.原式=m(16n4-1) =m(4n²+1)(4n²-1) =m(4n²+1)(2n+1)(2n-1)3.原式=x²+6x+8+1 =x²+6x+9 =(x+3)²4.原式=(a+b)²+2×2(a+b)+4 =(a+b+2)²
