Question

a的平方＋b的平方＋c的平方－ab－ac－bc怎样化简

Answer 1

a^2+b^2+c^2-ab-bc-ac

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

=[(a^2-2ab+b^2)+(b^2-2bc+c^2)+(c^2-2ca+a^2)]/2

=[(a-b)^2+(b-c)^2+(a-c)^2]/2