Question

ex 1 si 2 din poza va rog

Answer 1

Uite rezolvările. Succes!

Answer 2

Metoda de calcul

Pentru a determina necunoscuta, vom folosi proporțiile derivate.

Pentru ∀ a, b, c, d, dacă  $\frac{a}{b} = \frac{c}{d}$  rezultă că a*d = c*b.

Răspuns

1. a)

$\frac{2}{5} = \frac{4}{x} \\\\x = \frac{4 * 5}{2} = 10$

b)

$\frac{10}{x} = \frac{5}{6} \\\\x = \frac{10 * 6}{5} = \frac{60}{5} = 12$

c)

$\frac{x}{25} = \frac{2}{5} \\ \\x = \frac{2 * 25}{5} = 10$

d)

$\frac{3,5}{2,5} = \frac{x}{10} \\\\x = \frac{10 * 3,5}{2,5} = 14$

2. a)

$\frac{2}{x} = \frac{1}{\frac{7}{2} } \\\\x = \frac{2 * \frac{7}{2} }{1} = 7$

b)

$\frac{x}{\frac{3+14 : 7}{25} } = \frac{0,1 + 4,9}{(0,1)^{2} } \\\\x = \frac{\frac{3 + 14 : 7}{25} * 0,1 + 4,9 }{(0,1)^{2} } = \frac{\frac{1}{5} * 5}{0,01} = \frac{1}{\frac{1}{100} } = 100$

c)

$\frac{15}{5 * (1 - \frac{1}{5} )} = \frac{1}{x} \\\\x = \frac{5 * (1 - \frac{1}{5} )}{15} = \frac{4}{15}$

d)

$\frac{\frac{1}{3} }{x} = \frac{3 * [0,1(6) + 0,(3) + 0,25]}{1-\frac{1}{4} } \\\\x = \frac{\frac{1}{3} * (1 - \frac{1}{4} ) }{3 * (\frac{1}{6} + \frac{1}{3} + \frac{1}{4} )} = \frac{\frac{1}{4} }{3 * \frac{10}{12} } = \frac{\frac{1}{4} }{\frac{3}{4} } = \frac{1}{4} * \frac{4}{3} = \frac{1}{3}$

e)

$\frac{137137}{x} = \frac{137}{\frac{1}{1001} } \\\\x = \frac{137137 * \frac{1}{1001} }{137} = \frac{1001 * \frac{1}{1001} }{1} = 1$