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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
a)
`1/3+3/4+2/3+1/4`
`=1/3+2/3+3/4+1/4`
`=1+1`
`=2`
b)
`3/4+3/5+2/8+4/10`
`=3/4+2/8+3/5+4/10`
`=6/8+2/8+6/10+4/10`
`=1+1`
`=2`
c)
`1/10+2/10+3/10+4/10+5/10+6/10+7/10+8/10+9/10`
`=1/10+9/10+2/10+8/10+3/10+7/10+6/10+4/10+5/10`
`=1+1+1+1+5/10`
`=4+5/10`
`=40/10+5/10`
`=45/10=9/2`
a: =1/3+2/3+3/4+1/4
=1+1
=2
b: =3/4+1/4+3/5+2/5
=1+1
=2
c: =(1+2+3+4+5+6+7+8+9)/10
=45/10
=9/2
\(\dfrac{1}{2}+\dfrac{1}{3}-\dfrac{1}{5}=\dfrac{3+2}{6}-\dfrac{1}{5}=\dfrac{5}{6}-\dfrac{1}{5}=\dfrac{5\times5-6}{30}=\dfrac{19}{30}\\ \dfrac{1}{5}:4+\dfrac{3}{4}=\dfrac{1}{5}\times4+\dfrac{3}{4}=\dfrac{4}{5}+\dfrac{3}{4}=\dfrac{4\times4+3\times5}{20}=\dfrac{31}{20}\)
\(\dfrac{4}{3}\times\dfrac{9}{5}-\dfrac{3}{10}=\dfrac{36}{15}-\dfrac{3}{10}=\dfrac{12}{5}-\dfrac{3}{10}=\dfrac{12\times2-3}{10}=\dfrac{21}{10}\)
\(\dfrac{1}{2}\) + \(\dfrac{1}{3}\) - \(\dfrac{1}{5}\)
= \(\dfrac{1\times15}{2\times15}\) + \(\dfrac{1\times10}{3\times10}\) - \(\dfrac{1\times6}{5\times6}\)
= \(\dfrac{15}{30}\) + \(\dfrac{10}{30}\) - \(\dfrac{6}{30}\)
= \(\dfrac{19}{30}\)
\(\dfrac{1}{5}\) : 4 + \(\dfrac{3}{4}\)
= \(\dfrac{1}{5}\) \(\times\) \(\dfrac{1}{4}\) + \(\dfrac{3}{4}\)
= \(\dfrac{1}{20}\) + \(\dfrac{3\times5}{4\times5}\)
= \(\dfrac{1}{20}+\dfrac{15}{20}\)
= \(\dfrac{16}{20}\)
= \(\dfrac{4}{5}\)
\(\dfrac{4}{3}\) \(\times\) \(\dfrac{9}{5}\) - \(\dfrac{3}{10}\)
= \(\dfrac{12}{5}\) - \(\dfrac{3}{10}\)
= \(\dfrac{24}{10}\) - \(\dfrac{3}{10}\)
= \(\dfrac{21}{10}\)
Bài 1:
a: x+1/2=5/6
nên x=5/6-1/2=1/3
b: x+1/4=3/4
nên x=3/4-1/4=2/4=1/2
c: x+3/10=1/2
nên x=1/2-3/10=5/10-3/10=1/5
d: x+1/4=3/8
nên x=3/8-1/4=3/8-2/8=1/8
Bài 1: Tính
a, 1/2 x 2/3 x 3/4 = 1/4
b, 7/8 x 8/9 x 9/10 = 7/10
c, 5/14 x 7/15 x 28/7 = 2/3
d, 2 x 1/2 x 3 x 1/3 x 4 x 1/4 x 5 x 1/5 = 1
Bài 2: Tính
a, 7/20 - ( 5/8 - 3/5 ) = 7/20 - 1/40 = 14/40 - 1/40 = 13/40
b, 5/6 + ( 5/9 - 1/4 ) = 5/6 + 11/36 = 30/36 + 11/36 = 41/36
c, 9/10 - ( 2/5 + 3/10 ) + 7/20 = 9/10 - 7/10 + 7/20 = 2/10 + 7/20 = 4/20 + 7/20 = 11/20.
Bài 3: Tìm x:
a, 1/2 + x = 5/6
x = 5/6 - 1/2
x = 1/3
b, 5/6 - x = 1/3
x = 5/6 - 1/3
x = 1/2
c, x - 1/mấy vậy bạn
d, 1/3 x x = 1/6
x = 1/6 : 1/3
x = 1/2
1) 1/3 x 1/2 x 3/7 = 3/42 = 1/14
2) 5/4 x 1/3 +1/7 = 5/12 + 1/7 = 35/84 + 12/84 = 47/84
3) 8 x ( 8/9 - 2/3 ) = 8 x 2/9 = 16/9
4) 5/6 x 48/20 x 1/2 = 240/240 = 1
5) ( 2/5 + 3/4 ) + 8 = 23/20 + 8 = 23//20 + 160/20 = 183/20
6) 10 x ( 1/2 - 1/5 ) = 10 x 3/10 = 10/1 x 3/10 = 30/10 = 3
Bài làm
a) \(\left(\frac{1}{2}+\frac{4}{7}\right)-\left(\frac{3}{7}-\frac{3}{10}\right)\)
\(=\frac{1}{2}+\frac{4}{7}-\frac{3}{7}+\frac{3}{10}\)
\(=\frac{35}{70}+\frac{40}{70}-\frac{30}{70}+\frac{21}{70}\)
\(=\frac{66}{70}\)
\(=\frac{33}{35}\)
b) \(\left(\frac{3}{5}x\frac{4}{5}x\frac{5}{9}\right):\left(\frac{7}{9}-\frac{3}{5}\right)\)
\(=\left(\frac{1}{5}x\frac{4}{3}\right):\left(\frac{35}{45}-\frac{27}{45}\right)\)
\(=\frac{4}{15}:\frac{8}{45}\)
\(=\frac{4}{15}.\frac{45}{8}\)
\(=\frac{1}{1}.\frac{3}{2}\)
\(=\frac{3}{2}\)