LN
2
K
Khách
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HK
2
NH
24 tháng 9 2023
`x xx4/5 :2=6/7`
`x xx 4/5xx1/2=6/7`
`x xx2/5=6/7`
`x=6/7:2/5`
`x=6/7xx5/2`
`x=15/7`
b)
`6/5:x:5/4=10/15`
`6/5:x xx4/5=2/3`
`6/5:x=2/3:4/5`
`6/5:x=2/3xx5/4`
`6/5:x=5/6`
`x=6/5:5/6`
`x=6/5xx6/5`
`x=36/25`
KV
24 tháng 9 2023
a) x × 4/5 : 2 = 6/7
x × 4/5 = 6/7 × 2
x × 4/5 = 12/7
x = 12/7 : 4/5
x = 15/7
b) 6/5 : x : 5/4 = 10/15
6/5 : x : 5/4 = 2/3
6/5 : x = 2/3 × 5/4
6/5 : x = 5/6
x = 6/5 : 5/6
x = 36/25
6 tháng 7 2023
a: Sửa đề; \(A=\dfrac{7.2:2\cdot28.6+1.43\cdot2\cdot64}{1+3+5+7+...+49-339}\)
\(=\dfrac{3.6\cdot28.6+2.86\cdot64}{1+3+5+...+49-339}\)
\(=\dfrac{2.86\left(64+36\right)}{25^2-339}=\dfrac{286}{286}=1\)
b: =>2(x+7/8)=6*13/4=78/4=39/2
=>x+7/8=39/4
=>x=71/8
CN
3
NT
Nguyễn thành Đạt
CTVHS
20 tháng 9 2023
\(3\dfrac{7}{8}\times x-2\dfrac{3}{4}=3\dfrac{6}{12}\times\dfrac{10}{8}-\dfrac{1}{3}\)
\(\dfrac{31}{8}\times x-\dfrac{11}{4}=\dfrac{7}{2}\times\dfrac{10}{8}-\dfrac{1}{3}\)
\(\dfrac{31}{8}\times x-\dfrac{11}{4}=\dfrac{35}{8}-\dfrac{1}{3}\)
\(\dfrac{31}{8}\times x=\dfrac{97}{24}+\dfrac{11}{4}\)
\(\dfrac{31}{8}\times x=6\dfrac{19}{24}\)
\(x=1\dfrac{70}{93}\)
20 tháng 9 2023
42/12x10/8-1/3= 84/24x30/24-8/24= 315/72-8/24= 291/72
xong bạn rút gọn nha
NT
Nguyễn Thị Thương Hoài
Giáo viên
VIP
7 tháng 10 2023
Muốn làm những bài toán có chứa hỗn số thì em cần nhớ:
Bước 1: Chuyển các hỗn số có trong phép tính thành phân số.
Bước 2: Thực hiện phép tính theo thứ tự thực hiện phép tính
a, \(\dfrac{8\dfrac{1}{2}}{15:\dfrac{5}{17}}\)
= \(\dfrac{\dfrac{17}{2}}{15\times\dfrac{17}{5}}\)
= \(\dfrac{\dfrac{17}{2}}{3\times17}\)
= \(\dfrac{17}{2}\) x \(\dfrac{1}{3\times17}\)
= \(\dfrac{1}{6}\)
VQ
4 tháng 5 2022
\(\dfrac{1}{3}+\dfrac{2}{3}=\dfrac{3}{3}=1\)
\(\dfrac{4}{5}+\dfrac{5}{6}=\dfrac{24}{30}+\dfrac{25}{30}=\dfrac{49}{30}\)
\(\dfrac{4}{5}-\dfrac{3}{5}=\dfrac{1}{5}\)
\(\dfrac{8}{5}x\dfrac{5}{8}=\dfrac{1}{1}=1\)
\(\dfrac{6}{7}x\dfrac{4}{7}=\dfrac{24}{49}\)
\(\dfrac{4}{5}:\dfrac{4}{5}=\dfrac{4}{5}x\dfrac{5}{4}=\dfrac{1}{1}=1\)
\(\dfrac{5}{5}:\dfrac{5}{5}=\dfrac{5}{5}x\dfrac{5}{5}=\dfrac{1}{1}=1\)
O
4 tháng 5 2022
1) \(\dfrac{1}{3}+\dfrac{2}{3}=\dfrac{1+2}{3}=\dfrac{3}{3}=1\)
2) \(\dfrac{4}{5}+\dfrac{5}{6}=\dfrac{24}{30}+\dfrac{25}{30}=\dfrac{24+25}{30}=\dfrac{49}{30}\)
3) \(\dfrac{4}{5}-\dfrac{3}{5}=\dfrac{4-3}{5}=\dfrac{1}{5}\)
4) \(\dfrac{9}{8}-\dfrac{4}{2}=\dfrac{9}{8}-2=\dfrac{9}{8}-\dfrac{16}{8}=-\dfrac{7}{8}\)
5) \(\dfrac{8}{5}\times\dfrac{5}{8}=\dfrac{8\times5}{5\times8}=\dfrac{40}{40}=1\)
6) \(\dfrac{6}{7}\times\dfrac{4}{7}=\dfrac{6\times4}{7}=\dfrac{24}{7}\)
7) \(\dfrac{4}{5}:\dfrac{4}{5}=\dfrac{4}{5}\times\dfrac{5}{4}=\dfrac{4\times5}{5\times4}=\dfrac{20}{20}=1\)
8) \(\dfrac{5}{5}:\dfrac{5}{5}=\dfrac{5}{5}\times\dfrac{5}{5}=\dfrac{5\times5}{5\times5}=\dfrac{25}{25}=1\)
NV
3
16 tháng 6 2021
Giải:
\(\dfrac{1}{2}+\dfrac{2}{8}+\dfrac{3}{28}+\dfrac{4}{77}+\dfrac{5}{176}+\dfrac{6}{352}\)
\(=\dfrac{1}{1.2}+\dfrac{2}{2.4}+\dfrac{3}{4.7}+\dfrac{4}{7.11}+\dfrac{5}{11.16}+\dfrac{6}{16.22}\)
\(=\dfrac{1}{1}-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{11}+\dfrac{1}{11}-\dfrac{1}{16}+\dfrac{1}{16}-\dfrac{1}{22}\)
\(=\dfrac{1}{1}-\dfrac{1}{22}\)
\(=\dfrac{21}{22}\)
S
16 tháng 6 2021
\(\dfrac{1}{2}+\dfrac{2}{8}+\dfrac{3}{28}+\dfrac{4}{77}+\dfrac{5}{176}+\dfrac{6}{352}\\ =\dfrac{1}{2}+\dfrac{1}{4}+\dfrac{3}{28}+\dfrac{4}{77}+\dfrac{5}{176}+\dfrac{3}{176}\\ =\dfrac{3}{4}+\dfrac{3}{28}+\dfrac{4}{77}+\dfrac{1}{22}\\ =\dfrac{21}{28}+\dfrac{3}{28}+\dfrac{7}{154}+\dfrac{8}{154}\\ =\dfrac{6}{7}+\dfrac{15}{154}\\ =\dfrac{21}{22}\)
NT
Nguyễn Thị Thương Hoài
Giáo viên
VIP
5 tháng 8 2023
a, \(\dfrac{7}{8}\) \(\times\) \(\dfrac{3}{13}\) + \(\dfrac{4}{9}\) \(\times\) \(\dfrac{4}{13}\)
= \(\dfrac{1}{13}\) \(\times\)( \(\dfrac{21}{8}\) + \(\dfrac{16}{9}\))
= \(\dfrac{1}{13}\) \(\times\)( \(\dfrac{189}{72}\) + \(\dfrac{128}{72}\))
= \(\dfrac{1}{13}\) \(\times\) \(\dfrac{317}{73}\)
= \(\dfrac{317}{949}\)
b, \(\dfrac{6}{5}\) + \(\dfrac{7}{3}\) + \(\dfrac{8}{9}\)
= \(\dfrac{54}{45}\) + \(\dfrac{105}{45}\) + \(\dfrac{40}{45}\)
= \(\dfrac{199}{45}\)
c, 23 : \(\dfrac{5}{14}\) + \(\dfrac{6}{7}\) + \(\dfrac{4}{9}\)
= \(\dfrac{322}{5}\) + \(\dfrac{6}{7}\) + \(\dfrac{4}{9}\)
= \(\dfrac{20286}{315}\) + \(\dfrac{270}{315}\) + \(\dfrac{140}{315}\)
= \(\dfrac{20696}{315}\)
d, 4\(\dfrac{1}{4}\) + 7\(\dfrac{3}{7}\) - 2\(\dfrac{4}{17}\)
= 4 + \(\dfrac{1}{4}\) + 7 + \(\dfrac{3}{7}\) - 2 - \(\dfrac{4}{17}\)
= (4+7-2) + (\(\dfrac{1}{4}\) + \(\dfrac{3}{7}\) - \(\dfrac{4}{17}\))
= 9 + \(\dfrac{119}{476}\) + \(\dfrac{204}{476}\) - \(\dfrac{112}{476}\)
= 9\(\dfrac{211}{476}\) = \(\dfrac{4495}{476}\)
e, 8 - (9\(\dfrac{2}{11}\) + \(\dfrac{8}{33}\))
= 8 - 9 - \(\dfrac{2}{11}\) - \(\dfrac{8}{33}\)
= -1 - \(\dfrac{2}{11}\) - \(\dfrac{8}{33}\)
= \(\dfrac{-33}{33}\) - \(\dfrac{-6}{33}\) - \(\dfrac{8}{33}\)
= - \(\dfrac{47}{33}\)
BD
18 tháng 8 2023
\(\dfrac{1}{2}-\dfrac{2}{3}+\dfrac{3}{4}-\dfrac{4}{5}+\dfrac{5}{6}-\dfrac{6}{7}-\dfrac{6}{5}+\dfrac{4}{5}-\dfrac{3}{4}+\dfrac{2}{3}-\dfrac{1}{2}\)
\(=\left(\dfrac{1}{2}-\dfrac{1}{2}\right)+\left(-\dfrac{2}{3}+\dfrac{2}{3}\right)+\left(\dfrac{3}{4}-\dfrac{3}{4}\right)+\left(-\dfrac{4}{5}+\dfrac{4}{5}\right)+\left(\dfrac{5}{6}-\dfrac{6}{7}-\dfrac{6}{5}\right)\)
\(=0+0+0+0-\dfrac{257}{210}\)
\(=\dfrac{257}{210}\)
\(\dfrac{49}{28}:\dfrac{5}{4}.\dfrac{6}{7}=\dfrac{49}{28}.\dfrac{4}{5}.\dfrac{6}{7}=\dfrac{49.4.6}{28.5.7}=\dfrac{7.7.4.6}{4.7.5.7}=\dfrac{6}{5}\)
\(\dfrac{49}{28}:\dfrac{5}{4}\times\dfrac{6}{7}\)
= \(\dfrac{49}{28}\times\dfrac{4}{5}\times\dfrac{6}{7}\)
= \(\dfrac{7\times7}{4\times7}\) x \(\dfrac{4}{5}\) x \(\dfrac{6}{7}\)
= \(\dfrac{6}{5}\)