Hình mờ lắm ak bn!

Bài 1:

\(54\left(\dfrac{km}{h}\right)=15\left(\dfrac{m}{s}\right);9\left(\dfrac{m}{s}\right)=32,4\left(\dfrac{km}{h}\right)\)

Baì 2:

\(t'=s':v'=5:\left(5.3,6\right)=\dfrac{5}{18}h\)

\(\Rightarrow v_{tb}=\dfrac{s'+s''}{t'+t''}=\dfrac{5+3,8}{\dfrac{5}{18}+\left(\dfrac{15}{60}\right)}\simeq16,67\left(\dfrac{km}{h}\right)\)

Câu 2: 

\(\Leftrightarrow\left(x+2\right)\left(10x+3\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=-2\\x=-\dfrac{3}{10}\end{matrix}\right.\)

5.

1. going

2.lying/reading

3.likes/ being

4.collecting

5.watching / are going

6.doing

7.plays

8.have collected

9. will travel

10.will make

6.

1.beautiful

2. boring

3. decoration

4.widens

5. wonderful

8

\(a.720:\left(x-17\right)=12\)

\(x-17=60\)

\(x=77\)

\(b.\left(x-28\right):12=8\)

\(x-28=96\)

\(x=124\)

\(c.26+8x=6x+46\)

\(8x-6x=46-26\)

\(2x=20\)

\(x=10\)

\(d.3600:\left[\left(5x+335\right):x\right]=50\)

\(\left(5x+335\right):x=72\)

\(5+335:x=72\)

\(335:x=67\)

\(x=5\)

a) \(720:\left(x-17\right)=12\)

\(\Rightarrow x-17=\dfrac{720}{12}\)

\(\Rightarrow x-17=60\)

\(\Rightarrow x=60+17\)

\(\Rightarrow x=77\)

b) \(\left(x+28\right):12=8\)

\(\Rightarrow x+28=12\cdot8\)

\(\Rightarrow x+28=96\)

\(\Rightarrow x=96-28\)

\(\Rightarrow x=68\)

c) \(26+8x=6x+46\)

\(\Rightarrow8x-6x=46-26\)

\(\Rightarrow2x=20\)

\(\Rightarrow x=\dfrac{20}{2}\)

\(\Rightarrow x=10\)

d) \(3600:\left[\left(5x+335\right):x\right]=50\)

\(\Rightarrow\left(5x+335\right):x=\dfrac{3600}{50}\)

\(\Rightarrow\left(5x+335\right):x=72\)

\(\Rightarrow5x+335=72\cdot x\)

\(\Rightarrow72x-5x=335\)

\(\Rightarrow67x=335\)

\(\Rightarrow x=\dfrac{335}{67}\)

\(\Rightarrow x=5\)

7. How often does he go to the library?
8. ....is the shortest student in his class.
9......is her address?
10... is shorter than Ba.

7 how often does he go to the library

8 nga is the shortest student in the class

9 what is her adress

10 hoa is shorter than ba

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