Cho a thuộc Z . Tìm số nguyên x, biết: a) a + x = 3; b) a - x = 6

Read the following passage carefully, and then select the best option A, B, C or D to complete it

World Wide Web (WWW), computer-based (1) _______ of information resources that combines text and multimedia. The information on the World Wide Web can be accessed and searched through the (2) _______, a global computer network. The World Wide Web is often (3) _______ to simply as “the Web.”

The Web started to become a (4) _______ resource after 1993 when the first widely distributed browser provided a convenient way to (5) _______ a variety of information on the Internet. The Web uses (6) _______, which means that information can be displayed in a wide variety of formats. (7) _______ can read text, view pictures, watch animation, listen to sounds, and even explore interactive virtual environments on the Web. A user can (8) _______ seamlessly from a document or Web page stored on the computer to a document or Web page (9) _______ on another computer.

The Web offers a place where companies, universities and (10) _______ institutions, and individuals can display information about their products, services, facilities, or research, or their (11) _______ lives. Only a small percentage of information on the (12) _______ is restricted to subscribers or other authorized users. The majority of Web pages are available to (13) _______ who can access a computer that connects to the Internet. The Web has become a (14) _______ for many companies selling products or services, and a forum for people to exchange opinions and information. Museums, libraries, government agencies, and schools post information on the Web to make it (15) _______ to others.

Question 3:

A. said

B. referred

C. told

D. considered

Từ tháng 10 - 1940, Hít-le chuyển sang thôn tính các nước:

A. Tây và Nam châu Âu

B. Đông và Bắc châu Âu

C. Đông và Nam châu Âu

D. Tây và Bắc châu Âu

Kính lúp dùng để quan sát các vật có kích thước

A. nhỏ.

B. rất nhỏ.

C. lớn.

D. rất lớn.

dãy số có n số hạng

tổng của dạy số là (n+1) x n : 2= 465

n x (n+1)= 930

nhận thấy n và n+1 là hai số tự nhiên liên tiếp có 30 x31 = 930

vậy n = 930

\(\sqrt{108x^3}.\sqrt{3x}=\sqrt{108x^3.3x}=\sqrt{324x^4}=18x^2\)( vì x >= 0)

a. \(\sqrt{7}.\sqrt{63}=\sqrt{7.63}=\sqrt{441}=21\)

b.\(\sqrt{2,5}.\sqrt{30}.\sqrt{48}=\sqrt{2,5.30.48}=\sqrt{3600}=60\)

c.\(\sqrt{0,4}.\sqrt{6,4}=\sqrt{0,4.6,4}=\sqrt{2,56}=1,6\)

d.\(\sqrt{2,7}.\sqrt{5}.\sqrt{1,5}=\sqrt{2,7.5.1,5}=\sqrt{20,25}=4,5\)