Question

Сокращайте:
2a(a+b-c)-2b(a-b-c)+2c(a-b+c)

Answer 1

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