Question

计算(a+b+c）（a+b+c)+(a+b+c)^2

Answer 1

(a+b+c）（a+b+c)+(a+b+c)^2
=2(a+b+c)²
=2(a²+b²+c²+2ab+2ac+2bc)
=2a²+2b²+2c²+4ab+4ac+4bc

追问

(a+b+c)(a-b-c)+(a+b+c)^2

追答

(a+b+c)(a-b-c)+(a+b+c)^2
=[a+(b+c)][a-(b+c)]+[a+(b+c)]²
=a²-(b+c)²+a²+2a(b+c)+(b+c)²
=2a²+2ab+2ac