a) \(\dfrac{x-45}{55}+\dfrac{x-47}{53}=\dfrac{x-55}{45}+\dfrac{x-53}{47}\)

b)\(\dfrac{x+1}{2004}+\dfrac{x+2}{2003}=\dfrac{x+3}{2002}+\dfrac{x+4}{2001}\)

Bài 1:cho biểu thức C=\(\dfrac{x}{2x-2}\)+\(\dfrac{x^2+1}{2-2x^2}\)

a)Tìm x để C có nghĩa

b)Rút gọn C

c)Tìm x để C=\(\dfrac{1}{2}\)

Cho tam giác ABC,AD là phân giác góc A

Tính DC biết AB=4cm,AC=5cm,BC=3cm

Cho HCN MNDQ,vẽ NK vuông góc với MD

a)CMR:Tam giác KMN đồng dạng với Tam giác QPM và MN²=KM.PM

b)Gọi I là trung điểm của MK,E là trung điểm của KN

CMR:Tam giác IKE đồng dạng với Tam giác PQM và IK.PM=IE.PM

XI. Write the second sentence so that it has the same meaning to the first one.
1. Pollution affects the environment in many ways.
The environment_______________________________________________________
2. It’s impossible for us to predict when the earthquake will happen.
We__________________________________________________________________
3. Some farmers are overusing Chemicals in their crops.
Chemicals____________________________________________________________
4. Don’t leave the tap running while brushing your teeth, or you will waste water.
If you________________________________________________________________
5. Since the invention of special computers, the paths of hurricanes have been predicted.
Since special computers__________________________________________________
6. The weather is bad, so we can’t go hiking in the mountains.
If the weather__________________________________________________________
7. What was the height of the waves in the Japan tsunami 2011?
How_________________________________________________________________
8. It’s my opinion that you should study English in the UK.
If____________________________________________________________________
9. Global warming will affect specific regions in different ways.
Specific regions________________________________________________________
10. It’s two years since the Hawaii volcano erupted.
The Hawaii volcano_____________________________________________________