Bài 6: Thực hiện phép tính
a) $\frac{4}{9}$ x $\frac{7}{13}$ + $\frac{4}{9}$ x $\frac{8}{13}$ – $\frac{4}{13}$ x $\frac{2}{9}$
b) ($\frac{1}{5}$ – $\frac{1}{3}$ +$\frac{2}{15}$) : $\frac{2014}{2015}$
c)$\frac{2}{3}$ + $\frac{5}{8}$ – $\frac{-1}{3}$ + $\frac{375}{1000}$
Bài 6: Thực hiện phép tính a) $\frac{4}{9}$ x $\frac{7}{13}$ + $\frac{4}{9}$ x $\frac{8}{13}$ – $\frac{4}{13}$ x $\frac{2}{9}$ b) ($\frac{1}{5}$ – $\
By Eden
`a) 4/9 . 7/13 + 4/9 . 8/13 – 4/13 . 2/9`
` =4/9. (7/13 + 8/13) – 4/13 . 2/9`
` = 4/9 . 15/13 – 4/13 .2/9`
` = 2/9 . 2.15/13 – 4/13 . 2/9`
` = 2/9.( 2. 15/13 – 4/13)`
` = 2/9. ( 30/13 – 4/13)`
` = 2/9 . 2`
` = 4/9`
`b) (1/5 – 1/3 +2/15) : 2014/2015`
` = (3/15 – 5/15 + 2/15) : 2014/2015`
` = 0 : 2015`
` = 0`
`c) 2/3 + 5/8 – (-1)/3 + 375/1000`
` = (2/3 – (-1)/3) + (5/8 + 375/1000)`
` = (2/3 + 1/3) + ( 625/1000 + 375/1000)`
` = 1 + 1`
` = 2`
Đáp án + giải thích bước giải :
`a) 4/9 . 7/13 + 4/9 . 8/13 – 4/13 . 2/9`
`= 4/9 . (7/13 + 8/13) – 4/13 . 2/9`
`= 4/9 . 15/13 – 4/13 . 2/9`
`= 20/39 – 8/117`
`= 4/9`
`b) (1/5 – 1/3 + 2/15) : 2014/2015`
`= ((-2)/15 + 2/15) . 2015/2014`
`= 0 . 2015/2014`
`= 0`
`c) 2/3 + 5/8 – (-1)/3 + 375/1000`
`= 2/3 + 5/8 + 1/3 + 375/1000`
`= 31/24 + 1/3 + 375/1000`
`= 13/8 + 375/1000`
`= 2`