Consider the variation of the Wyndor Glass Co. example represented in Fig. 13.5, where the second and third functional constraints of the original problem (see Sec. 3.1) have been replaced by 9x12 + 5x22 ≤ 216. Demonstrate that (x1, x2) = (2, 6) with Z = 36 is indeed optimal by showing that the objective function line 36 = 3x1 + 5x2 is tangent to this constraint boundary at (2, 6).