Choose the letter A, B, C, D for each gap in the following sentence.

I'll come home ....................... 8.30 and 9.20.

A. at

B. in

C. between

D. on

Read the passage and answer the questions

(1) __________ near the southern margin of the Red River Delta, the Trang An Landscape Complex is a spectacular landscape. Exploration of caves at different altitudes has revealed archaeological traces of human activity over a continuous period of more (2) __________ 30,000 years. They illustrate the occupation of these mountains by seasonal hunter-gatherers and how they adapted (3) ___________ major climatic and environmental changes, especially the repeated inundation of the landscape by the sea after the last ice age. The story of human occupation continues through the Neolithic and Bronze Ages to the historical era. Hoa Lu, the ancient (4) ___________ of Viet Nam, was strategically established here in the 10th and 11th centuries AD. The property also contains temples, pagodas, paddy-fields and small villages.

Question 1:

A. Situated

B. Situate

C. Situating

D. To situate

Theo quan điểm của chủ nghĩa Mác – Lê nin, các nước tiền tư bản tư bản tiến hành đi lên chủ nghĩa xã hội là thực hiện hình thức quá độ

A. Toàn diện

B. Lâu dài

C. Trực tiếp

D. Gián tiếp

<=>x.27=-2.3,6=-7,2

<=>x=-4/15

nhớ tick nha

a) \(5\sqrt{a}-4b\sqrt{25a^3}+5a\sqrt{16ab^2}-2\sqrt{9a}\)

=\(5\sqrt{a}-4b.5a\sqrt{a}+5a.4b\sqrt{a}-2.3\sqrt{a}\)

=\(5\sqrt{a}-20ab\sqrt{a}+20ab\sqrt{a}-6\sqrt{a}\)

=\(5\sqrt{a}-6\sqrt{a}=-\sqrt{a}\)

b) \(5a\sqrt{64ab^3}-\sqrt{3}.\sqrt{12a^3b^3}+2ab\sqrt{9ab}-5b\sqrt{81a^3b}\)

=\(5a.8b\sqrt{a}-6ab\sqrt{ab}+2ab.3\sqrt{ab}-5b.9a\sqrt{b}\)

=\(40ab\sqrt{ab}-6ab\sqrt{ab}+6ab\sqrt{ab}-45ab\sqrt{ab}\)

=\(-5ab\sqrt{ab}\)

=> x + 19 chia hết cho x + 5

x + 5 + 14 chia hết cho x + 5

Hay 14 chia hết cho x + 5

x + 5 thuộc Ư(14) = {1;2;7;14}

Mà n là số tự nhiên nên n = 2 ; 9

M=(\(\dfrac{\sqrt{x}}{\sqrt{x}-x}-\dfrac{\sqrt{x}+2}{1-x}=\dfrac{\sqrt{x}}{\sqrt{x}\left(1-\sqrt{x}\right)}-\dfrac{\sqrt{x}+2}{\left(1-\sqrt{x}\right)\left(1+\sqrt{x}\right)}\))

M = \(\left(\dfrac{\sqrt{x}\left(1+\sqrt{x}\right)}{\sqrt{x}\left(1-\sqrt{x}\right)\left(1+\sqrt{x}\right)}\right)-\dfrac{\left(\sqrt{x}+2\right)\sqrt{x}}{\left(1-\sqrt{x}\right)\left(1+\sqrt{x}\right)\sqrt{x}}\)

M=\(\dfrac{\sqrt{x}\left(1+\sqrt{x}\right)-\left(\sqrt{x}+2\right)\sqrt{x}}{\sqrt{x}\left(1-\sqrt{x}\right)\left(1+\sqrt{x}\right)}\)=\(\dfrac{\sqrt{x}+x-x-2\sqrt{x}}{\sqrt{x}\left(1-x\right)}\)

M=\(\dfrac{\sqrt{x}-2\sqrt{x}}{\sqrt{x}\left(1-x\right)}=\dfrac{-\sqrt{x}}{\sqrt{x}\left(1-x\right)}=\dfrac{-1}{1-x}\)

M= \(\dfrac{-1}{1-x}\) có giá trị nguyên khi 1-x là ước của -1

Các ước của -1 là :

1-x=1 suy ra x=0(loại)

1-x= -1 suy ra x=2

B=\(\dfrac{1}{\sqrt{3}-1}-\dfrac{1}{\sqrt{3+1}}=\dfrac{1}{\sqrt{3}-1}-\dfrac{1}{\sqrt{4}}=\dfrac{1}{\sqrt{3}-1}-\dfrac{1}{2}\)

B=\(\dfrac{2}{2\left(\sqrt{3}-1\right)}-\dfrac{\sqrt{3}-1}{2\left(\sqrt{3}-1\right)}=\dfrac{2-\left(\sqrt{3}-1\right)}{2\left(\sqrt{3}-1\right)}\)

B=\(\dfrac{2-\sqrt{3}+1}{2\left(\sqrt{3}-1\right)}=\dfrac{3-\sqrt{3}}{2\left(\sqrt{3}-1\right)}=\dfrac{\sqrt{3}\left(\sqrt{3}-1\right)}{2\left(\sqrt{3}-1\right)}\)

B=\(\dfrac{\sqrt{3}}{2}\)