tính giá trị biểu thức
4 - 4/9 -[2 1/4 + 1 4/9]
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DT
3
C
23 tháng 5 2022
\(\dfrac{4}{5}-\dfrac{2}{5}\times\dfrac{1}{4}=\dfrac{4}{5}-\dfrac{1}{10}=\dfrac{8}{10}-\dfrac{1}{10}=\dfrac{7}{10}\)
\(\dfrac{1}{4}+\dfrac{3}{4}:\dfrac{1}{8}=\dfrac{1}{4}+\dfrac{3}{4}\times8=\dfrac{1}{4}+6=\dfrac{1}{4}+\dfrac{24}{4}=\dfrac{25}{4}\)
\(\)\(\dfrac{11}{10}-\dfrac{2}{5}:\dfrac{1}{3}=\dfrac{11}{10}-\dfrac{2}{5}\times3=\dfrac{11}{10}-\dfrac{6}{5}=\dfrac{11}{10}-\dfrac{12}{10}=-\dfrac{1}{10}\)
23 tháng 5 2022
4/5-2/5.1/4
=4/5-1/10
=8/10-1/10
=7/10
1/4+3/4:1/8
=1/4+3/4.8
=1/4+6
=1/4+24/4
=25/4
11/10-2/5:1/3
=11/10-2/5.3
=11/10-6/5
=11/10-12/10
=-1/10
NV
1
H
18 tháng 4 2023
`a, 3/4 + 1/2 xx 7/2`
`= 3/4 + 7/4`
`=10/4`
`=5/2`
`b, 6/15 - 1/3 : 5/3`
`= 6/15 - 1/3 xx 3/5`
`= 6/15 - 3/15`
`= 3/15`
`=1/5`
`c, x-4/9 = 3/7 : 9/4`
`=> x-4/9= 3/7 xx 4/9`
`=> x-4/9= 12/63`
`=> x-4/9=4/21`
`=> x= 4/21 +4/9`
`=>x= 40/63`
`d, 7/9 xx 3/5 -1/2=1/5`
`->` sao lại bằng có `x` ko vậy ạ?
18 tháng 4 2023
`a,`
`3/4+1/2 \times 7/2=3/4+7/4=10/4=5/2`
`b,`
`6/15 - 1/3 \div 5/3=6/15-1/5=1/5`
`c,` Tìm x?
`x-4/9=3/7 \div 9/4`
`x-4/9=4/21`
`x=4/21+4/9`
`x=40/63`
`d, 7/9x \times 3/5-1/2=1/5`
`7/9x \times 3/5=1/5+1/2`
`7/9x \times 3/5=7/10`
`7/9x=7/10 \div 3/5`
`7/9x=7/6`
`x=7/6 \div 7/9=3/2`
UM
2
4 tháng 2 2017
\(\left(\frac{9}{10}+\frac{1}{10}\div\frac{4}{5}\right)\times\left(\frac{3}{15}-\frac{2}{15}\times\frac{4}{3}\times\frac{9}{8}\right)\)
\(=\left(1\div\frac{4}{5}\right)\times\left(\frac{3}{15}-\frac{1}{5}\right)\)
\(=\frac{5}{4}\times0\)
\(=0\)
KN
2
21 tháng 4 2022
2/5 + 3/4 - 4/7 = 23/20 - 4/7 = 81/140
7/9 : 2/3 x 5/4 = 7/6 x 5/4 = 35/24
4/5 x (7/10 - 1/2) = 4/5 x 1/5 = 4/25
KV
21 tháng 4 2022
a) \(\dfrac{2}{5}+\dfrac{3}{4}-\dfrac{4}{7}\)
\(=\dfrac{56}{140}+\dfrac{105}{140}-\dfrac{80}{140}\)
\(=\dfrac{56+105-80}{140}\)
\(=\dfrac{81}{140}\)
b) \(\dfrac{7}{9}:\dfrac{2}{3}\times\dfrac{5}{4}\)
\(=\dfrac{7}{9}\times\dfrac{3}{2}\times\dfrac{5}{4}\)
\(=\dfrac{7\times3\times5}{9\times2\times4}\)
\(=\dfrac{35}{24}\)
c) \(\dfrac{4}{5}\times\left(\dfrac{7}{10}-\dfrac{1}{2}\right)\)
\(=\dfrac{4}{5}\times\left(\dfrac{7}{10}-\dfrac{5}{10}\right)\)
\(=\dfrac{4}{5}\times\dfrac{1}{5}\)
\(=\dfrac{4}{25}\)
AS
4
12 tháng 1 2020
\(\frac{1}{2\times3}+\frac{1}{3\times4}+\frac{1}{4\times5}+...+\frac{1}{9\times10}\)
\(=\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{9}-\frac{1}{10}\)
\(=\frac{1}{2}-\frac{1}{10}=\frac{2}{5}\)
DY
1
5 tháng 5 2019
\(\frac{9}{1.2}+\frac{9}{2.3}+\frac{9}{3.4}+...+\frac{9}{99.100}\)
=\(9.\left(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{99.100}\right)\)
=\(9.\left(\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{99}-\frac{1}{100}\right)\)
=\(9.\left(\frac{1}{1}-\frac{1}{100}\right)\)
=\(9.\frac{99}{100}\)
=\(\frac{891}{100}\)
LP
1
4-\(\frac{4}{9}\)- [\(2\frac{1}{4}\)+1\(\frac{4}{9}\)]
=\(4-\frac{4}{9}-2\frac{1}{4}-1\frac{4}{9}\)
=\(\left(4-2\frac{1}{4}\right)-\left(\frac{4}{9}-1\frac{4}{9}\right)\)
=\(1\frac{3}{4}-\left(-1\right)\)
=\(2\frac{3}{4}\)