MA
2
K
Khách
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MA
2
LL
17 tháng 9 2017
\(A\)\(\left(1-\frac{1}{3}\right)\)\(\cdot\)\(\left(1-\frac{1}{4}\right)\)\(\cdot\)\(\left(1-\frac{1}{5}\right)\)
\(=\frac{2}{3}\)\(\cdot\frac{3}{4}\)\(\cdot\frac{4}{5}\)
\(=\frac{2}{5}\)
\(B\)\(\left(1+\frac{1}{3}\right)\)\(\cdot\left(1+\frac{1}{4}\right)\)\(\cdot\left(1+\frac{1}{5}\right)\)
\(=\)\(\frac{4}{3}\)\(\cdot\frac{5}{4}\)\(\cdot\frac{6}{5}\)
\(=\)\(2\)
DH
1
TN
19 tháng 6 2020
Bài 1: Tính
a) =1\(\frac{49}{60}\)
b) =2\(\frac{13}{30}\)
Bài 2: Tìm x
a) =4\(\frac{1}{21}\)
Riêng câu b) thì mk nghĩ là bạn viết lộn vì mk thấy cái chỗ xx3/4 là mk ko hiểu rồi
KV
4 tháng 11 2023
Bài 1
a) 3 2/5 - 1/2
= 17/5 - 1/2
= 34/10 - 5/10
= 29/10
b) 4/5 + 1/5 × 3/4
= 4/5 + 3/20
= 16/20 + 3/20
= 19/20
c) 3 1/2 × 1 1/7
= 7/2 × 8/7
= 4
d) 4 1/6 : 2 1/3
= 25/6 : 7/3
= 25/14
KV
4 tháng 11 2023
Bài 2
a) 3 × 1/2 + 1/4 × 1/3
= 3/2 + 1/12
= 18/12 + 1/12
= 19/12
b) 1 4/5 - 2/3 : 2 1/3
= 9/5 - 2/3 : 7/3
= 9/5 - 2/7
= 63/35 - 10/35
= 53/35
YC
15 tháng 4 2021
Bài 2:
a,4x25x0,25x\(\frac{1}{5}\) x \(\frac{1}{2}\) x 2
=4x25x0,25x0,2x0,5x2
=(4x0,25)+(25x0,2)+(0,5x2)
= 1 + 5 1
=7
15 tháng 4 2021
X + 1/2 + X + 1/4 + X + 1/8 + X + 1/8 +X +1/16
= X + 8/16 + X + 4/16 + X + 2/16 + X + 2/16 +X + 1/16
= X + ( 8/16 + 4/16 + 2/16 + 2/16 ) + X +1/16
= X + 1 + X + 1/16
= X + ( 1 + 1/16 )
= X + 1 VÀ 1/16
NH
1
31 tháng 8 2020
a) \(x+\frac{1}{5}-\frac{2}{7}=4\frac{1}{2}\)
=> \(x+\frac{1}{5}-\frac{2}{7}=\frac{9}{2}\)
=> \(x=\frac{9}{2}+\frac{2}{7}-\frac{1}{5}=\frac{321}{70}\)
b) \(1\frac{3}{4}+x-\frac{7}{8}=5\)
=> \(\frac{7}{4}+x-\frac{7}{8}=5\)
=> \(\frac{7}{4}+x=\frac{47}{8}\)
=> \(x=\frac{33}{8}\)
c) \(\frac{1}{2}-\frac{1}{3}\cdot x=\frac{3}{4}\)
=> \(\frac{1}{3}\cdot x=\frac{1}{2}-\frac{3}{4}=-\frac{1}{4}\)
=> \(x=\left(-\frac{1}{4}\right):\frac{1}{3}=\left(-\frac{1}{4}\right)\cdot3=-\frac{3}{4}\)
LM
Lê Minh Vũ
CTVHS
5 tháng 6 2023
\(3\dfrac{1}{2}+4\dfrac{5}{7}-5\dfrac{5}{14}\)
= \(\dfrac{7}{2}+\dfrac{33}{7}-\dfrac{75}{14}\)
= \(\dfrac{49}{14}+\dfrac{66}{14}-\dfrac{75}{14}\)
= \(\dfrac{40}{14}=\dfrac{20}{7}\)
\(4\dfrac{1}{2}+\dfrac{1}{2}\div5\dfrac{1}{2}\)
=\(\dfrac{9}{2}+\dfrac{1}{2}\div\dfrac{11}{2}\)
=\(\dfrac{9}{2}+\dfrac{1}{2}\times\dfrac{2}{11}\)
=\(\dfrac{9}{2}+\dfrac{1}{11}\)
=\(\dfrac{101}{22}\)
\(x\times3\dfrac{1}{3}=3\dfrac{1}{3}\div4\dfrac{1}{4}\)
\(x\times\dfrac{10}{3}=\dfrac{10}{3}\div\dfrac{17}{4}\)
\(x\times\dfrac{10}{3}=\dfrac{10}{3}\times\dfrac{4}{17}\)
\(x\times\dfrac{10}{3}=\dfrac{40}{51}\)
\(x=\dfrac{40}{51}\div\dfrac{10}{3}\)
\(x=\dfrac{40}{51}\times\dfrac{3}{10}\)
\(x=\dfrac{120}{510}=\dfrac{12}{51}=\dfrac{4}{7}\)
\(5\dfrac{2}{3}\div x=3\dfrac{2}{3}-2\dfrac{1}{2}\)
\(\dfrac{17}{3}\div x=\dfrac{11}{3}-\dfrac{5}{2}\)
\(\dfrac{17}{3}\div x=\dfrac{7}{6}\)
\(x=\dfrac{17}{3}\div\dfrac{7}{6}\)
\(x=\dfrac{17}{3}\times\dfrac{6}{7}\)
\(x=\dfrac{102}{21}=\dfrac{34}{7}\)
7 tháng 6 2018
Bài 3:
= 1- 1/2 + 1/2 -1/3 +...+ 1/98 -1/99
= 1- 1/99
= 98/99
Bài 4:
= 1/2*3 + 1/3*4 + 1/4*5 +...+ 1/10*11
= 1/2 - 1/3 + 1/3 - 1/4 + 1/4 - 1/5 +...+ 1/10 - 1/11
= 1/2 - 1/11= 9/22
20 tháng 8 2018
a) \(\frac{1}{2}\times\frac{1}{3}+\frac{1}{3}\times\frac{1}{4}+\frac{1}{4}\times\frac{1}{5}+\frac{1}{5}\times\frac{1}{6}=\frac{1}{2\times3}+\frac{1}{3\times4}+\frac{1}{4\times5}+\frac{1}{5\times6}\)
\(=\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}\)
\(=\frac{1}{2}-\frac{1}{6}=\frac{3}{6}-\frac{1}{6}=\frac{2}{6}=\frac{1}{3}\)
b) \(\left(1-\frac{1}{2}\right)\left(1-\frac{1}{3}\right)\left(1-\frac{1}{4}\right)=\frac{1}{2}\times\frac{2}{3}\times\frac{3}{4}=\frac{1}{4}\)
D
20 tháng 8 2018
\(a)\frac{1}{2}\times\frac{1}{3}+\frac{1}{3}\times\frac{1}{4}+\frac{1}{4}\times\frac{1}{5}+\frac{1}{5}\times\frac{1}{6}\)
\(\Rightarrow\frac{1}{2\times3}+\frac{1}{3\times4}+\frac{1}{4\times5}+\frac{1}{5\times6}\)
\(\Rightarrow\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}\)
\(\Rightarrow\frac{1}{2}-\frac{1}{6}\)
\(\Rightarrow\frac{1}{3}\)
\(b)\left(1-\frac{1}{2}\right)\times\left(1-\frac{1}{3}\right)\times\left(1-\frac{1}{4}\right)\)
\(=\frac{1}{2}\times\frac{2}{3}\times\frac{3}{4}\)
\(=\frac{1\times2\times3}{2\times3\times4}\)
\(=\frac{1}{4}\)
\(b)\left(1-\frac{1}{2}\right)\div\left(1-\frac{1}{3}\right)\div\left(1-\frac{1}{4}\right)\)
\(=\frac{1}{2}\div\frac{2}{3}\div\frac{3}{4}\)
\(=\frac{1}{2}\times\frac{3}{2}\times\frac{4}{3}\)
\(=\frac{1\times3\times2\times2}{2\times2\times3}\)
\(=1\)
a,=2/5
b,=2
A) = \(\frac{2}{5}\)
B) = 2