Question

[(2,5 : 1,25 - 1,2 la a doua):0,9-0,2×(2 la a doua- 1,8 la a doua)] :0,04

Answer 1

$[(2,5 : 1,25 - {1,2}^{2}) : 0,9 - 0,2 \times ( {2}^{2} - {1,8}^{2})] : 0,04 = \\ \\ 2,5 = \frac{25}{10} = \frac{5}{2} \\ \\ 1,25 = \frac{125}{100} = \frac{5}{4} \\ \\ \frac{5}{2} \times \frac{4}{5} = \frac{5 \times 4}{2 \times 5} = \frac{20}{10} = 2 \\ \\ 1,2 = \frac{12}{10} = \frac{6}{5} \\ \\ {1,2}^{2} = \frac{ {6}^{2} }{ {5}^{2} } = \frac{36}{25} \\ \\ 2 - \frac{36}{25} = \frac{2}{1} - \frac{36}{25} = \frac{2 \times 25}{1 \times 25} - \frac{36}{25} = \frac{50}{25} - \frac{36}{25} = \frac{50 - 36}{25} = \frac{14}{25} \\ \\ 0,9 = \frac{9}{10} \\ \\ \frac{14}{25} : 0,9 = \frac{14}{25} \times \frac{10}{9} = \frac{14 \times 10}{25 \times 9} = \frac{140}{225} = \frac{28}{45} \\ \\ {2}^{2} = 4 \\ \\ 1,8 = \frac{18}{10} = \frac{9}{5} \\ \\ {1,8}^{2} = \frac{ {9}^{2} }{ {5}^{2} } = \frac{81}{25} \\ \\ 4 - \frac{81}{25} = \frac{4}{1} - \frac{81}{25} = \frac{4 \times 25}{1 \times 25} - \frac{81}{25} = \frac{100}{25} - \frac{81}{25} = \frac{100 - 81}{25} = \frac{19}{25} \\ \\ 0,2 = \frac{2}{10} = \frac{1}{5} \\ \\ 0,2 \times \frac{19}{25} = \frac{1 \times 19}{5 \times 25} = \frac{19}{125} \\ \\ \frac{28}{45} - \frac{19}{125} = \frac{28 \times 25}{45 \times 25} - \frac{19 \times 9}{125 \times 9} = \frac{700}{1125} - \frac{171}{1125} = \frac{700 - 171}{1125} = \frac{529}{1125} \\ \\ 0,04 = \frac{4}{100} = \frac{1}{25} \\ \\ \frac{529}{1125} : 0,04 = \frac{529}{1125} \times \frac{25}{1} = \frac{529 \times 25}{1125 \times 1} = \frac{13225}{1125} = \frac{529}{45}$