三个数相加的平方怎么因式分解（三个数的平方加减公式）

(a+b+c)²

=[(a+b)+c]²

=(a+b)²+2(a+b)c+c²

=a²+b²+c²+2ab+2ac+2bc

(a+b+c)²

=[(a+b)+c]²

=(a+b)²+2(a+b)c+c²

=a²+b²+c²+2ab+2ac+2bc

(a+b+c)²

=[(a+b)+c]²

=(a+b)²+2(a+b)c+c²

=a²+b²+c²+2ab+2ac+2bc

(a+b+c)²

=[(a+b)+c]²

=(a+b)²+2(a+b)c+c²

=a²+b²+c²+2ab+2ac+2bc

(a+b+c)²

=[(a+b)+c]²

=(a+b)²+2(a+b)c+c²

=a²+b²+c²+2ab+2ac+2bc