[tex] (2x-y)^{2} = 4x^{2} -4xy+ y^{2} [/tex]
[tex] \frac{x}{3} +2 y^{3} +? = \frac{x}{3} +2 y^{3} +2* \sqrt{2} y^{ \frac{3}{2} } * \sqrt{ \frac{x}{3} } = ( \sqrt{ \frac{x}{3} }+ \sqrt{2} y^{ \frac{3}{2} } ) ^{2} [/tex]
[tex] (3x-2y+ \sqrt{5} )^{2} =9 x^{2} +4 y^{2} +5-12xy+6 \sqrt{5} x-4 \sqrt{5} y[/tex]
