Срочно сделать.......Плиз

$8. \\ c ^{2} = a^{2} + b^{2} \\ c^{2} = 5 ^{2} + 12 ^{2} = 25 + 144 = 169 \\ c = \sqrt{169} = 13$

$6. \\ 1000 - 8 = 992 \\ 992 \div 32 = 31$
$5. \\ log_{3}(8.1) + log_{3}(10) = log_{3}(8.1 \times 10) = log_{3}(81) = 4$

$1. \\ (3 \frac{1}{5} + 2) \div 1.3 = \\ ( \frac{3}{5} + 2) \div 1.3 = \\ (\frac{3}{5} + 2) \div \frac{13}{10} = \\ \frac{13}{5} \div \frac{13}{10} = \\ \frac{13}{5} \times \frac{10}{13} = \frac{10}{5} = 2$

4.
S= 1/2 * 12 * 5 * 5/6= 6 * 5 * 5/6= 5*5 = 25