(a-b+c）²公式是什么？ (a+b+c)(a+b-c)公式是什么？
(a-b+c\uff09²\u516c\u5f0f\u662f\u4ec0\u4e48\uff1f1(a-b+c\uff09²
=a²+b²+c²-2ab+2ac+2bc
a^2+2ab+b^2-c^2
\u5206\u6790\uff1a
(a+b+c)(a+b-c)
=\uff08a+b\uff09²-c² \u5e73\u65b9\u5dee
=a^2+2ab+b^2-c^2
\u6269\u5c55\u8d44\u6599
\u5176\u4ed6\u76f8\u5173\u516c\u5f0f\uff1a
\uff081\uff09\uff08a+b\uff09³\uff1da³\uff0b3a²b\uff0b3ab²\uff0bb³
\uff082\uff09a³+b³=a³+a²b-a²b+b³=a²\uff08a+b\uff09-b\uff08a²-b²\uff09=a²\uff08a+b\uff09-b\uff08a+b\uff09\uff08a-b\uff09
=\uff08a+b\uff09[a²-b\uff08a-b\uff09]=\uff08a+b\uff09\uff08a²-ab+b²\uff09
\uff083\uff09a³-b³=a³-a²b+a²b-b³=a²\uff08a-b\uff09+b\uff08a²-b²\uff09=a²\uff08a-b\uff09+b\uff08a+b\uff09\uff08a-b\uff09
=\uff08a-b\uff09[a²+b\uff08a+b\uff09]=\uff08a-b\uff09\uff08a²+ab+b²\uff09
将(a-b+c)²中的a-b看成整体m，变成(m+c)²，运用平方和公式展开得到：
m²+2mc+c²再把m=a-b代入得到：(a-b)²+2c(a-b)+c²
运用平方差公式将第一项展开，同时乘法分配律展开第二项得到：a²-2ab+b²+2ac-2bc+c²
可以把高次写前面，混合项写后面，也即：a²+b²+c²-2ab+2ac-2bc
（a-b+c）²=[(a-b)+c]² =(a-b)²+2(a-b)c+c² =a²-2ab+b²+2ac-2bc+c² =a²+b²+c²-2ab+2ac-2bc
绛旓細搴旇鏄繍鐢細鍗佸瓧鐩镐箻娉 (a -b)脳(a -c)=a ²+(-b -c)a +(-b )脳(-c)=a²-(b +c)a +bc
绛旓細璇佹槑杩囩▼濡備笅锛氳瘉鏄庯細(A-B)鈭(A鈭C)={(A-B)鈭狝}鈭﹞(A-B)鈭狢} =A鈭﹞(A-B)鈭狢} =(A-B)鈭狝C =(A鈭〤uB)鈭狝C =A-Cu{CuB鈭狢)} =A-(B鈭〤uC)=A-(B-C)
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