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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-2c)(a-b-2c);化简并计算1(1+y+x)(1-x-y)-(x+y)(x-y);2(2x-y-3)(2x-y+3)-(2x-y-3

题目详情
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-2c)(a-b-2c);化简并计算【1】(1+y+x)(1-x-y)-(x+y)(x-y);【2】(2x-y-3)(2x-y+3)-(2x-y-3)?
▼优质解答
答案和解析
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-2x��2] 原式= [2x-y]��-9 - [2x-y]��- 9+ 6[2x-y] = 12x - 6y -18