Вычислите с помощью формулы a^2-b^2=(a-b)(a+b): (5/12)^2-(3/4)^2.

\[\left( \frac{5}{12} \right)^{2} - \left( \frac{3}{4} \right)^{2} = \left( \frac{5}{12} \right)^{2} - \left( \frac{9}{12} \right)^{2} =\]

\[= \left( \frac{5}{12} - \frac{9}{12} \right)\left( \frac{5}{12} + \frac{9}{12} \right) =\]

\[= - \frac{4}{12} \cdot \frac{14}{12} = - \frac{7}{3 \cdot 6} = - \frac{7}{18}.\]