Giúp mình với làm ơn
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làm giúp mình với mình làm ơn đó ạ
18 tháng 10 2021
\(\dfrac{x}{-3}=\dfrac{y}{7}\Rightarrow\dfrac{x}{6}=\dfrac{y}{-14};\dfrac{y}{-2}=\dfrac{z}{5}\Rightarrow\dfrac{y}{-14}=\dfrac{z}{35}\\ \Rightarrow\dfrac{x}{6}=\dfrac{y}{-14}=\dfrac{z}{35}\)
Áp dụng t/c dtsbn:
\(\dfrac{x}{6}=\dfrac{y}{-14}=\dfrac{z}{35}=\dfrac{2x}{12}=\dfrac{4y}{-56}=\dfrac{5z}{175}=\dfrac{-2x-4y+5z}{-12+56+175}=\dfrac{146}{219}=\dfrac{2}{3}\\ \Rightarrow\left\{{}\begin{matrix}x=6\cdot\dfrac{2}{3}=4\\y=-14\cdot\dfrac{2}{3}=-\dfrac{28}{3}\\z=35\cdot\dfrac{2}{3}=\dfrac{70}{3}\end{matrix}\right.\)
25 tháng 12 2021
x/-3=y/7;y/-2=z/5 và -2x-4y+5z=146
BCNN(7,2)=14
=>x/-3=y/7;y/-2=z/5
=>x/-3=y/7=>x/6=y/14(1)
=>y/-2=z/5=>y/-14=z/35(2)
từ(1) và (2) =>x/6=y/-14=z/35 và -2x-4y+5z=146
Sử dụng tính chất dãy tỉ số bằng nhau:
=>x/6=y/-14=z/35=>-2x-4y+5z/(-2).6-4.(-14)+5.35=146/219=2/3
=>x/6=2/3=>x=2.6/3=4
=>y/-14=2/3=>y=-14.2/3=-28/3
=>z/35=2/3=>z=35.2/3=70/3
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17 tháng 8 2021
Em tách ra 1-2 bài/1 câu hỏi để mọi người hỗ trợ nhanh nhất nha!
23 Rice has been grown in this region since ancient time
24 The mouse was chased by the cat
25 Small fish are often eaten by big fish
26 You will be informed of the test result next week
27 Most of the houses in the village were destroyed by the earthquake
28 Mark Twan's book has been read by millions of people
29 You won't be allowed to enter this building
30 The meaning of a smile can be understood
32 The pyramids were built along the Nile by Ancient Egyptians
33 Perfume has been worn since ancient times
34 Her kid was told not to go out at night
35 His students were advised to choose the suitable course
36 Ba was asked by Thu to help her
37 We were taught how to pronounce these difficilt words by Ms Brown
38 I was allowed to join in the trip
39 Summer is said to be the best season of the year
40 Lan's team was announced to win the contest by her
41 His school was said to spend a lot of time for the match
42 Phong was told to do the washing up by his father
43 The newcomers were said to become earlier in the morning
44 New Year Day is celebrated according to the Lunar Calendar by the Vietnamese
45 The Spring Fair was organized at Tao Dan Park last year
46 Matches weren't used to make the fire
47 You will be showed how to find a book by the libririan
48 Which house has just been built?
49 How many tons of rice are exported?
50 What can be seen from this tower?
51 Paper is made in this factory
52 Several festival are celebrated by us every year
53 The bike can be fixed by Ba
Question 7
1 Is cotton exported to many countries by Egypt
2 People decorated the Christmas trees and put them at the front door
3 Something must be done for these poor man
4 Was the novel "Martin Idon" written by Jack London
5 They are going to build a new supermarket next year
6 A new chruch has just been built near my house
7 French and English are spoken in Canada
8 The telephone was invented by Bell in 1876
9 He is said to be the best doctor
10 New Arts Gallery will exhibit his painting for the first time