bài 1 tính
2/5+1/15+3/10
1/2-1/8-1/16
1/4-1/7+1/28
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Bài 7:
Số phần kẹo Hùng đã cho Hà và Hồng là:
\(\dfrac{2}{7}+\dfrac{1}{7}=\dfrac{3}{7}\left(phần\right)\)
Hùng còn lại số phần của gói kẹo là:
\(\dfrac{6}{7}-\dfrac{3}{7}=\dfrac{3}{7}\left(phần\right)\)
1:
2 3/4
5 6/5
3 3/9
7 6/8
2:
1/3 + 2/3 + (3/4 + 1/4) = 2
=2
= 4 5/10
`2/5+1/4`
`=8/20+5/20`
`=13/20`
__
`1/3+3/5`
`=5/15+9/15`
`=14/15`
__
`1/2+1/4`
`=2/4+1/4`
`=3/4`
__
`1/8+5/6`
`=6/48+40/48`
`=46/48`
`=23/24`
2/5 + 1/4
= 8/20 + 5/20
= 13/20
1/3 + 3/5
= 5/15 + 9/15
= 14/15
1/2 + 1/4
= 2/4 + 1/4
= 3/4
1/8 + 5/6
= 6/48 + 40/48
= 46/48
= 23/24
\(\dfrac{-2}{5}+\left(\dfrac{4}{6}-\dfrac{1}{15}\right)-\dfrac{-1}{10}\\ =\dfrac{-2}{5}+\dfrac{3}{5}+\dfrac{1}{10}\\ =\dfrac{1}{5}+\dfrac{1}{10}\\ =\dfrac{3}{10}\\ \dfrac{1}{2}-\left(\dfrac{-7}{3}+\dfrac{2}{5}\right)+\dfrac{1}{8}\\ =\dfrac{1}{2}+\dfrac{29}{15}+\dfrac{1}{8}\\ =\dfrac{73}{30}\\ =\dfrac{73}{30}+\dfrac{1}{8}\\ =\dfrac{307}{120}\)
\(-\dfrac{2}{5}+\left(\dfrac{4}{6}-\dfrac{1}{15}\right)-\left(-\dfrac{1}{10}\right)\)
\(=-\dfrac{2}{5}+\dfrac{3}{5}+\dfrac{1}{10}\)
\(=\dfrac{1}{5}+\dfrac{1}{10}\)
\(=\dfrac{2}{10}+\dfrac{1}{10}=\dfrac{3}{10}\)
\(\dfrac{1}{2}-\left(-\dfrac{7}{3}+\dfrac{2}{5}\right)+\dfrac{1}{8}\)
\(=\dfrac{1}{2}+\dfrac{29}{15}+\dfrac{1}{8}\)
\(=\dfrac{73}{30}+\dfrac{1}{8}=\dfrac{307}{120}\)
b, 3/5 + 4/7 + 2/8 + 10/25 + 9/21 + 28/16
= 3/5 + 4/7 + 2/8 + 2/5 + 3/7 + 14/8
= (3/5 + 2/5) + ( 4/7 + 3/7) + ( 2/8 + 14/8)
= 1 + 1 + 7/4
= 2 + 7/4 = 15/4
c , 8/7 + 7/6 + 5/8 + 10/12 + 24/28 + 6/16
= c , 8/7 + 7/6 + 5/8 + 5/6 + 6/7 + 1/2
= (8/7 + 6/7) + (7/6 + 5/6) + 5/8 + 1/2
= 14/7 + 12/6 + 5/8 + 1/2
= 2 + 2 + 5/8 + 1/2
= 4 + 9/8 = 41/8
a.-1,75-(-\(\dfrac{1}{9}\)-2\(\dfrac{1}{8}\))
-1,75-\(\dfrac{1}{9}+\dfrac{17}{8}\)
\(-\dfrac{7}{4}-\dfrac{1}{9}+\dfrac{17}{8}\)
\(\dfrac{-126}{72}-\dfrac{8}{72}+\dfrac{153}{72}\)
=\(\dfrac{19}{72}\)
b.\(\dfrac{-1}{12}-\left(2\dfrac{5}{8}-\dfrac{1}{3}\right)\)
\(\dfrac{-1}{12}-\left(\dfrac{21}{8}-\dfrac{1}{3}\right)\)
\(\dfrac{-1}{12}-\dfrac{21}{8}+\dfrac{1}{3}\)
\(\dfrac{-2}{24}-\dfrac{63}{24}+\dfrac{64}{24}\)
=\(\dfrac{-1}{24}\)
\(\frac{2}{5}+\frac{1}{15}+\frac{3}{10}=\frac{12}{30}+\frac{2}{30}+\frac{9}{30}=\frac{23}{30}\)
\(\frac{1}{2}-\frac{1}{8}-\frac{1}{16}=\frac{8}{16}-\frac{2}{16}-\frac{1}{16}=\frac{5}{16}\)
\(\frac{1}{4}-\frac{1}{7}+\frac{1}{28}=\frac{7}{28}-\frac{4}{28}+\frac{1}{28}=\frac{3}{28}+\frac{1}{28}=\frac{4}{28}=\frac{1}{7}\)