Tìm GTNN: P = ((x^2 + 12)/(x + y)) + y; D = (16/3 - x) + (3/x)

a) Tìm GTNN: P = ((x^2 + 12)/(x + y)) + y
b) Tìm GTNN: D = (16/3 - x) + (3/x)