Question

利用乘法公式计算(a+b+c)^2？

求大神来帮忙

Answer 1

（a+b+c)^2=a^2+2a*(b+c)+(b+c)^2=a^2+2ab+2ac+b^2+2bc+c^2

Answer 2

(a+b+c)²
=【（a+b）+c】²
=（a+b）²+2（a+b）c+c²
=a²+2ab+b²+2ac+2bc+c²