What is a ^ 2 + B ^ 2 + C ^ 2-ab-bc-ac reduced to?

What is a ^ 2 + B ^ 2 + C ^ 2-ab-bc-ac reduced to?

This is the result of the simplification. If you push backward, this is the result of the result of the reduction, and if you push backward, this is like this: A: A & \35353535353535\\\35\\\35\35\\35\\\\\\; + B & \\\\\\\\178;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; = (1 / 2) [(a-b) &