505

1. $$(\frac{x}{2}-\frac{y}{3})^2 = \frac{x^2}{4} - \frac{xy}{3} + \frac{y^2}{9}$$
2. $$(\frac{a}{4}+\frac{b}{3})^2 = \frac{a^2}{16} + \frac{ab}{6} + \frac{b^2}{9}$$
3. $$(2\frac{1}{3}m+1\frac{1}{2}n)^2 = (\frac{7}{3}m+\frac{3}{2}n)^2 = \frac{49}{9}m^2 + \frac{7}{1}mn + \frac{9}{4}n^2$$