Câu 6: Trang 113 toán VNEN lớp 5 tập 2
Tính:
a. $\frac{2}{5}$ + $\frac{3}{4}$ $\frac{7}{12}$ - $\frac{2}{7}$ + $\frac{1}{12}$ $\frac{12}{17}$ - $\frac{5}{17}$ - $\frac{4}{17}$
b. 675,39 + 342,14 563,87 + 403,13 - 328,35
Bài Làm:
a. $\frac{2}{5}$ + $\frac{3}{4}$ $\frac{7}{12}$ - $\frac{2}{7}$ + $\frac{1}{12}$ $\frac{12}{17}$ - $\frac{5}{17}$ - $\frac{4}{17}$
- $\frac{2}{5}$ + $\frac{3}{4} =\frac{(2\times 4)+(3\times 5)}{20}= \frac{23}{20}$
- $\frac{7}{12}$ - $\frac{2}{7}$ + $\frac{1}{12}$ = ($\frac{7}{12}$ + $\frac{1}{12}$) - $\frac{2}{7}$ = $\frac{8}{12}$ - $\frac{2}{7}$ = $\frac{32}{84}$=$\frac{3}{7}$
- $\frac{12}{17}-\frac{5}{17}-\frac{4}{17}=\frac{12-5-4}{17}=\frac{3}{17}$
b.
