Question

整式的乘法——添括号法则计算【1】（x+y-1）（x+y+1）；【2】（x+2y-1）（x-2y+1）；【3】（a+b-

Answer 1

1] [x+y-1 ][x+y+1] = [x+y]-1 = x+y+2xy-12] [x+2y-1][x-2y+1]= x-[2y-1]=x-4y-1+4y3] [a+b-2c][a-b-2c]= [a-2c]-b=a-4ac+4c-b 1] 原式= 1- [x+y] -[x-y] = 1-2xy-2x2] 原式= [2x-y]-9 - [2x-y]- 9+ 6[2x-y] = 12x - 6y -18