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1) 1/3 x 1/2 x 3/7 = 1/6 x 3/7 = 1/14
2) 5/4 x 1/3 + 1/7 = 5/12 + 1/7 = 47/84
3) 8 x (8/9 - 2/3) = 8 x 2/9 = 16/9
4) 5/6 x 48/20 x 1/2 = 2 x 1/2 = 1
5) (2/5 + 3/4) x 8 = 23/20 x 8 = 46/5
6) 10 x (1/2 - 1/5) = 10 x 3/10 = 3
4 x 2 x 5 = ?
Cách 1: 4 x 2 x 5 = (4 x 2) x 5 = 8 x 5 = 40
Cách 2: 4 x 2 x 5 = 4 x (2 x 5) = 4 x 10 = 40
7 x 2 x 3 = ?
Cách 1: 7 x 2 x 3 = (7 x 2) x 3 = 14 x 3 = 42
Cách 2: 7 x 2 x 3 = 7 x (2 x 3) = 7 x 6 = 42
6 x 3 x 3 = ?
Cách 1: 6 x 3 x 3 = (6 x 3) x 3 = 18 x 3 = 54
Cách 2: 6 x 3 x 3 = 6 x (3 x 3) = 6 x 9 = 54
6 x 2 x 4 = ?
Cách 1: 6 x 2 x 4 = (6 x 2) x 4 = 12 x 4 = 48
Cách 2: 6 x 2 x 4 = 6 x (2 x 4) = 6 x 8 = 48
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 1
1/2 x 3/4 : 4/5
= 3/8 : 4/5
= 3/8 x 5/4
= 15/32
2/3 + 1/6 - 1/2
= 4/6 + 1/6 - 3/6
= 5/6 - 3/6
= 1/3
3/5 + 4 : 2/3 - 3/2
= 3/5 + 4 x 3/2 - 3/2
= 3/5 + 6 - 3/2
= 3/5 + 30/5 - 3/2
= 33/5 - 3/2
= 66/10 - 15/10
= 28/5
Bài 2
x - 1/4 = 1/2
x = 1/2 + 1/4
x = 2/4 + 1/4
x = 3/4
2/3 + x = 1
x = 1 - 2/3
x = 3/3 - 2/3
x = 1/3
\(\frac{2}{3}\cdot\frac{3}{4}\cdot\frac{4}{5}:\frac{1}{5}\)
\(=\frac{1}{2}\cdot4\)
\(=2\)
\(\frac{1\cdot2\cdot3\cdot4}{5\cdot6\cdot7\cdot8}=\frac{1\cdot1\cdot3\cdot1}{5\cdot3\cdot7\cdot2}=\frac{1\cdot1\cdot1\cdot1}{5\cdot1\cdot7\cdot2}=\frac{1}{70}\)
\(\frac{2}{5}\cdot\frac{3}{4}\cdot\frac{5}{6}:\frac{3}{4}\)
\(=\frac{2}{5}\cdot\frac{5}{6}\cdot\frac{3}{4}:\frac{3}{4}\)
\(=\frac{1}{3}\cdot1\)
\(=\frac{1}{3}\)
\(\frac{2}{3}\times\frac{3}{4}\times\frac{4}{5}\div\frac{5}{1}\)
\(\frac{2}{3}\times\frac{3}{4}\times\frac{4}{5}\times\frac{5}{1}\)
\(=\frac{2}{1}=2\)
Các phần khác tương tự nhé em , nếu ko biết giải qua tin nhắn chị gửi cho
a) \(\dfrac{1}{2}+x=\dfrac{5}{6}\)
\(\Rightarrow x=\dfrac{5}{6}-\dfrac{1}{2}=\dfrac{5}{6}-\dfrac{3}{6}=\dfrac{2}{6}=\dfrac{1}{3}\)
b) \(x+\dfrac{1}{4}=\dfrac{3}{4}\)
\(\Rightarrow x=\dfrac{3}{4}-\dfrac{1}{4}=\dfrac{2}{4}=\dfrac{1}{2}\)
c) \(x-\dfrac{1}{5}=\dfrac{3}{10}\)
\(\Rightarrow x=\dfrac{3}{10}+\dfrac{1}{5}=\dfrac{3}{10}+\dfrac{2}{10}=\dfrac{5}{10}=\dfrac{1}{2}\)
d) \(\dfrac{5}{6}-x=\dfrac{1}{3}\)
\(\Rightarrow x=\dfrac{5}{6}-\dfrac{1}{3}=\dfrac{5}{6}-\dfrac{2}{6}=\dfrac{3}{6}=\dfrac{1}{2}\)
e) \(\dfrac{3}{10}+x=\dfrac{1}{2}\)
\(\Rightarrow x=\dfrac{1}{2}-\dfrac{3}{10}=\dfrac{5}{10}-\dfrac{3}{10}=\dfrac{2}{10}=\dfrac{1}{5}\)
g) \(x+\dfrac{1}{4}=\dfrac{3}{8}\)
\(\Rightarrow x=\dfrac{3}{8}-\dfrac{1}{4}=\dfrac{3}{8}-\dfrac{2}{8}=\dfrac{1}{8}\)
a) 12+x=5612+x=56
⇒x=56−12=56−36=26=13⇒x=56−12=56−36=26=13
b) x+14=34x+14=34
⇒x=34−14=24=12⇒x=34−14=24=12
c) x−15=310x−15=310
⇒x=310+15=310+210=510=12⇒x=310+15=310+210=510=12
d) 56−x=1356−x=13
⇒x=56−13=56−26=36=12⇒x=56−13=56−26=36=12
e) 310+x=12310+x=12
⇒x=12−310=510−310=210=15⇒x=12−310=510−310=210=15
g) x+14=38x+14=38
⇒x=38−14=38−28=18⇒x=38−14=38−28=18
Đọc tiếp
1: \(=\dfrac{1}{3}\cdot\dfrac{3}{7}\cdot\dfrac{1}{2}=\dfrac{1}{7\cdot2}=\dfrac{1}{14}\)
2: =5/12+1/7
=35/84+12/84=47/84
3: =8(8/9-6/9)
=8*2/9=16/9
4: \(=\dfrac{5}{12}\cdot\dfrac{12}{5}=1\)
5: =16/5+6
=16/5+30/5=46/5
6: =10*1/2-10*1/5
=5-2=3
\(\frac{2}{3}\times\frac{3}{4}\times\frac{4}{5}:\frac{1}{5}\)
\(=\frac{1}{2}\times\frac{4}{5}:\frac{1}{5}\)
\(=\frac{2}{5}:\frac{1}{5}\)
\(=2\)
a) 2/3 x 3/4 x 4/5 : 1/5
= 1/2 x 4
= 2
b) 1 x 2 x 3 x 4/5 x 6 x 7 x 8
= 2 x 3 x 24/5 x 56
= 6 x 72/5 x 56
= 432/5 x 56
= 24192/5
c) 2/5 x 3/4 x 5/6 : 3/4
= 3/10 x 10/9
= 1/3
Theo công thức tính dãy số ta có :
\(x\cdot\frac{(x+1)}{2}=5050\)
\(x\cdot(x+1)=10100\)
\(\Rightarrow x=100\)
x = 100