唱天谣壮文:初中数学题目

来源:百度文库 编辑:高校问答 时间:2024/05/01 05:58:40
(1-m²)(1-n²)-4mn
怎么算,要过程!!紧急!!

1-n²-m²+m²n²-4mn
=(1-2mn+m²n²)-(n²-2mn+m²)
=(1-mn)²-(n-m)²
(1-mn-n+m)(1-mn+n-m)

(1-m²)(1-n²)-4mn
= 1-m²-n²+m²n²-4mn
= 1-(m²+2mn+n²)+m²n²-2mn
= -(m+n)²+1-2mn+m²n²
= -(m+n)²+(1-mn)²
= (1-mn)²-(m+n)²
= (1-mn+m+n)(1-mn-m-n)