Question

Дам 45 баллов.
Найдите значение выражения 1 и 3​

Answer 1

1)

$(\frac{1}{4a} +\frac{1}{5a}) *\frac{a^{2}}{9} =(\frac{5}{20a} +\frac{4}{20a} )*\frac{a^{2}}{9}=\frac{9}{20a}*\frac{a^{2}}{9} =\frac{a}{20}$

$\frac{7.8}{20} =0.39$

3)

$\frac{a^{2}-25b^{2}}{5ab} :(\frac{1}{5b} -\frac{1}{a} )=\frac{(a-5b)(a+5b)}{5ab} :(\frac{a}{5ab} -\frac{5b}{5ab} )=\frac{(a-5b)(a+5b)}{5ab} :\frac{a-5b}{5ab} =\\\\\frac{(a-5b)(a+5b)}{5ab}*\frac{5ab}{a-5b} =a+5b$

$8\frac{1}{16} +5*6\frac{3}{16} =\frac{129}{16} +5*\frac{99}{16} =\frac{129}{16} +\frac{495}{16} =39$