[tex]9^{2}\cdot(-\dfrac{2}{3})^{3}\cdot\dfrac{1}{2}-(-0,5)^{2} = 81\cdot(-\dfrac{2^{3}}{3^{3}})\cdot\dfrac{1}{2}-(-\dfrac{1}{2})^{2} =81\cdot(-\dfrac{8}{27})\cdot\dfrac{1}{2}-\dfrac{1}{4}=\\\\\\=3\cdot(-8)\cdot\dfrac{1}{2}-\dfrac{1}{4}=3\cdot(-4)-\dfrac{1}{4} = -12-\dfrac{1}{4} =\boxed{ -12\frac{1}{4}}[/tex]
