$\frac{\sqrt{\mathrm{x}}}{\sqrt{\mathrm{x}}+3}+\frac{2\sqrt{x}}{\sqrt{x}-3}-\frac{3x+9}{x-9}$

Biết sin48$°$ $\approx$ 0.7431 . Tính sin42$°$

cho hình thang abcd (ab // cd) . vẽ bh$\perp$cd. (h thuộc cd )

cho biết bh=12cm, dh=16cm, ch=9cm, ad=14cm.

a. tính độ dài db, bc.

b. cm tam giác dbc vuông

c. tính các góc của hình thang abcd (làm tròn đến độ)

Gọi chữ số hàng đơn vị của một số tự nhiên có hai chữ số là xx thì điều kiện của xx là:
 A.
x∈Nx∈ℕ  và  0≤x≤90≤x≤9
 B.
x∈Nx∈ℕ và 0<x≤90<x≤9
 C.
0≤x≤90≤x≤9
 D.
x∈N

Cho tam giác ABC, lấy M thuộc AB, N thuộc AC. Biết MN//BC và AM=2cm; MB=3cm; BC=6,5cm. Khi đó độ dài cạnh MN là:
 A.
2,6cm
 B.
5cm
 C.
32cm32cm
 D.
1,5cm

Cho ΔABC∆ABC có AB=15cm; AC= 20cm. Đường phân giác góc BAC cắt cạnh BC tại D. Biết BD=9cm, độ dài đoạn thẳng DC bằng: 
 A.
6cm
 B.
3cm
 C.
12cm
 D.
18cm

II. Read the passage and choose the best answer

The United States is a large country. It is the third largest in the whole world! It is located in a continent called North America. Parts of the United States touch three different oceans. The United States has tall mountains, wide plains, deserts, hills, rivers, lakes, volcanoes and even rainforests! People from all over the world have come to live in the United States. There are 50 states in the United States. The newest states, Alaska and Hawaii, are not connected to the other states. Alaska is the largest state and Hawaii is a chain of islands in the Pacific Ocean.

1.The United States is the _________ country in the world. 

A.   second largest   B.largest        C.smallest     D.third largest

2.Alaska is ___________ and Hawaii is __________.

A. a chain of islands/ the largest state    B. the largest state/ a chain of islands

C.a chain of islands/ the largest state     D.not connected to the other states/ the largest state

3.The United States does not have ____________.

A.50 states                B. volcanoes             C. mountains                       D.continents

4.Parts of the United States touch _________ different oceans.

A.1                   B.2                   C.4                  D.3

5.What continent is the United States in?

A.North America                  B.Australia                C. Africa         D.Europe

READING

I, Read the passage and choose the correct answer A, B, C or D.

        Water Pollution in India

Contamination of water from any external source that makes it (1)                to life is known as water pollution. (2)                      the fast industrial development and modem civilization, the problem of water pollution is (3)                      day by day. The (4)               sources of water pollution are domestic wastes, agricultural wastes, sewage disposal, industrial wastes, radioactive wastes and oil leakages.

All the Indian rivers. including the holy river Ganga, have become highly polluted today. However, the Ganga Action Plan to control its water from pollution has not been proved (5)   .  The (6)              of water pollution is widespread. It causes many severe water- borne diseases.

According to WHO, 21 per cent of all (7)    diseases in India are water-borne diseases. Oil is the main pollutant of the sea water. Huge tankers often dump oil into the sea. This act of dumping (8)   kills sea plants and animals.

1. A. harm            B. harmful                       C. harmless                           D. unharmed

2.A. At                 B. Of                                  C. In                                        D. With

3. A. increase    B. increasing                   C. increased                          D. to increase       

4. A. most           B. more                            C. major                                 D. hard       

5. A.success      B. successful                  C. unsuccessful                    D. succeeded

6. A. effect          B. effects                         C. affect                                  D. affects

7. A. communicate  B. communicative    C. communicable                 D. communication

8. A. poisons      B.poisonous                    C. poisoning                          D. poisoned

 Find a mistake in each sentence in A, B, C, or D.
1.My father worked (A) in a noisy factory for (B) a long time, since (C) he suffered from hearing loss (D).

2.The River Thames flows (A) through southern (B) England and connect (C) London with (D)the sea.

3.Much (A) of the town was reconstruct (B) after (C) the tornado (D).

4.Look at (A) those (B) grey clouds! It will (C) rain soon (D).

$\sqrt{\mathrm{x}}\times \sqrt{x}$

$\left(\begin{array}{c}1\\ \sqrt{\mathrm{x}}\end{array}+\frac{\sqrt{\mathrm{x}}}{\sqrt{\mathrm{x}}+1}\right) ÷ \frac{\sqrt{x}}{x+\sqrt{x}}$

một số tử số bé hơn mẫu số là 11 . Nếu tăng tư lên 3 đơn vị và giảm mẫu số đi 4 đơn vị thì được một phân số bằng $\frac{3}{4}$ . Tìm phân số ban đầu 

cho hcn abcd . kẻ ah vuông góc với bd tại h

a. cm tam giác abh   tam giác bdc

b. cho ab=20cm ; ad=15cm . tính độ dài bd, bh

c. cmr: $\frac{1}{{\mathrm{ab}}^2}+\frac{1}{a{d}^2}\ge \frac{4}{b{d}^2}$ . tìm dk của hcn abcd để xảy ra dấu đẳng thức

cho hcn abcd . kẻ ah vuông góc với bd tại h

a. cm tam giác abh $~$ tam giác bdc

b. cho ab=20cm ; ad=15cm . tính độ dài bd, bh

tính biểu thức : $\frac{3+\sqrt{\mathrm{x}}}{3-\sqrt{\mathrm{x}}}$ tại x=36

$\sqrt{9{\mathrm{x}}^2-6\mathrm{x}+1}=2$

$2\sqrt{\mathrm{x}}-\sqrt{50}=0$

$\sqrt{9(\mathrm{x}-1)}=21$

cho tam giác abc vuông tại a . biết ab=6cm ; tanB=$\frac{5}{12}$ . Tính ac , bc

Cho hình chữ nhật abcd . Từ d hạ đường vuông góc với ac , cắt ac tại h. Biết rằng ab=13cm , dh=5cm . Tính độ dài bd