Вычислите с помощью формулы a^2-b^2=(a-b)(a+b): (5/6)^2-(2/3)^2.

\[\left( \frac{5}{6} \right)^{2} - \left( \frac{2}{3} \right)^{2} = \left( \frac{5}{6} \right)^{2} - \left( \frac{4}{6} \right)^{2} =\]

\[= \left( \frac{5}{6} - \frac{4}{6} \right)\left( \frac{5}{6} + \frac{4}{6} \right) =\]

\[= \frac{1}{6} \cdot \frac{9}{6} = \frac{1}{4} = 0,25.\]