1、(2x?)×(3xy?) =6x^4 y?
2、1/2ab?(2a?b — 3ab?)=a?b? - 3/2a?b^4
3、(5m - 4n )(4m - 5n) =25m?-16n?
4、(4x - 5y)?=16x?-40xy+25y?
5、102? =(100+2)?=100?+400+2?=10404
6、(x - 3)(x+3)(x?+9)=(x?-9)(x?+9) =x^4-81
二、因式分解
1、5X? - 10x? =5x?(x-2)
2、9m? - 4n?=(3m+2n)(3m-2n)
3、x?+10x+25 =(x+5)?
4、16m? - 8m+1=(4m-1)?