研究所、轉學考(插大)-微積分題庫

【非選題】
18. Find the minimum value =__⑱__ of f(x, y, z) = x² + y² + z² subject to constraints x + 2z = 6, x + y = 12, x ≥ 0, y ≥ 0, and z ≥ 0.