Compare the size of a * + b * + C * and ab + BC + AC. * = 2

Compare the size of a * + b * + C * and ab + BC + AC. * = 2

Multiply the two formulas by 2 and subtract them, that is, 2A * + 2B * + 2C * - 2 (AB + BC + AC) = (a * - 2Ab + b * + (a * - 2Ac + C *) + (b * - 2BC + C *) = (a-b) * + (A-C) * + (B-C) * is greater than or equal to 0, so the previous formula is greater than or equal to the following formula