Giải câu 1 bài : Luyện tập sgk Toán 5 trang 160

Câu 1: Trang 160 sgk toán lớp 5

Tính:

a) + \(\frac{3}{5}\) ;

- \(\frac{2}{7}\) + \(\frac{1}{12}\) ;

- \(\frac{5}{17}\) - \(\frac{4}{17}\) ;

b) 578,69 + 281,78 ;

594,72 + 406,38 - 329,47.

Bài làm:

a) + \(\frac{3}{5}\) = \(\frac{2 \times 5}{3 \times 5}\) + \(\frac{3 \times 3}{5 \times 3}\)

= + \(\frac{9}{15}\) = \(\frac{19}{15}\)

- \(\frac{2}{7}\) + \(\frac{1}{12}\) = ( + \(\frac{1}{12}\)) - \(\frac{2}{7}\) = \(\frac{8}{12}\) - \(\frac{2}{7}\) = \(\frac{2}{3}\) - \(\frac{2}{7}\) = \(\frac{2 \times 7}{3 \times 7}\) - \(\frac{2 \times 3}{7 \times 3}\) = \(\frac{14}{21}\) - \(\frac{6}{21}\)

= .

- \(\frac{5}{17}\) - \(\frac{4}{17}\) = - (\(\frac{5}{17}\) + \(\frac{4}{17}\)) = - \(\frac{9}{17}\) = \(\frac{3}{17}\) ;

b)

578,69 + 281,78 = 860,47.

594,72 + 406,38 - 329,47 = 1001,1 - 329,47 = 671,63.