Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks. Fill in the appropriate word in question 26

My first job was a sales assistant at a large department store. I wanted to work part–time, because I was still studying at university and I was only able to work a few nights a week.

I came across the advertisement in the local newspaper. I remember the interview as though it were yesterday. The (23) ______ manager sat behind a large desk. He asked me various questions which surprised me because all I wanted was to work in sales. An hours later, I was told that I had got the job and was given a contract to go over. I was to be trained for ten days before I took my post. Also, as a member of staff, I was (24) ______ to some benefits, including discounts.

When I eventually started, I was responsible (25) ______ the toy section. I really enjoyed it there and I oved demonstrating the different toys. I was surprised at how friendly my colleagues were, too. They made working there fun even when we had to deal with customers (26) ______ got on our nerves. (27) ______, working there was a great experience which I will never forget.

A. which

B. why

C. when

D. who

Hòa tan hoàn toàn 99,2 gam một mẫu thép (chỉ gồm Fe và C) trong dung dịch H₂SO₄ đặc nóng, thu được 65,52 lít hỗn hợp khí (SO₂ là sản phẩm khử duy nhất của S⁺⁶, ở đktc). Hàm lượng C trong mẫu thép trên là

A. 1,93%

B. 1,45%

C. 1,69%

D. 1,21%

\(3^x+3^{x+1}+3^{x+2}=117\)

\(\Rightarrow3^x+3^x.3+3^x.9=117\)

\(\Rightarrow3^x.\left(1+3+9\right)=117\)

\(\Rightarrow3^x.13=117\)

\(\Rightarrow3^x=117:13\)

\(\Rightarrow3^x=9\)

\(\Rightarrow3^x=3^2\)

\(\Rightarrow x=2\)

Vậy \(x=2\)

Đặt \(A=\dfrac{a}{a+b}+\dfrac{b}{b+c}+\dfrac{c}{c+a}\)

Vì \(a,b,c\in Z\)*

\(\Rightarrow\dfrac{a}{a+b}>\dfrac{a}{a+b+c}\)

Nên: \(\dfrac{b}{b+c}>\dfrac{b}{b+c+a};\dfrac{c}{c+a}>\dfrac{c}{c+a+b}\)

Vậy\(A=\)\(\dfrac{a}{a+b}+\dfrac{b}{b+c}+\dfrac{c}{c+a}>\dfrac{a+b+c}{a+b+c}=1\)

\(\Rightarrow A>1\)(1)

Lại có :\(\dfrac{a}{a+b}< \dfrac{a+b}{a+b+c}\)

Nên:\(\dfrac{b}{b+c}< \dfrac{b+c}{b+c+a};\dfrac{c}{c+a}< \dfrac{c+a}{c+a+b}\)

Vậy\(\dfrac{a}{a+b}+\dfrac{b}{b+c}+\dfrac{c}{c+a}< \dfrac{a+b+b+c+c+a}{a+b+c}\)

=\(\dfrac{2.\left(a+b+c\right)}{a+b+c}=2\)

\(\Rightarrow A< 2\)(2)

Từ (1) và (2) \(\Rightarrow1< \dfrac{a}{a+b}+\dfrac{b}{b+c}+\dfrac{c}{c+a}< 2\)

\(\Rightarrow A\) không phải là số nguyên

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the best option for each of the blanks. Fill in the appropriate word in question 24

The Rocky Mountains run almost the length of North America. They start in the North West, but lie only a (24) _____ hundred miles from the centre in the more southern areas. Although the Rockies are smaller (25) _____ the Alps, they are no less beautiful.

There are many roads across the Rockies, but the best way to see them is to travel by train. You start from Vancouver, the most attractive of Canada’s big cities. Standing with its feet in the water and its (26) ______in the mountains, this city (27) ______ its residents to ski on slopes just 15 minutes by car from the city centre.

Thirty passenger trains a day used to (28) _____ off from Vancouver on the cross–continent railway. Now there are just three a week, but the ride is still a great adventure. You sleep on board, which is fun, but travel through some of the best site at night.

A. many

B. few

C. lot

D. couple

Ta có:\(A=\dfrac{2n^2+4n+5}{n+1}\)

\(=\dfrac{\left(2n^2+2n\right)+\left(2n+2\right)+3}{n+1}\)

\(=\dfrac{2n.\left(n+1\right)+2.\left(n+1\right)+3}{n+1}\)

Để \(A\) nhận giá trị nguyên thì:

\(n+1\in\left\{\pm1;\pm3\right\}\)

\(TH1:\)\(n+1=1\Rightarrow n=0\)

\(TH2:n+1=-1\Rightarrow n=-2\)

\(TH3:n+1=3\Rightarrow n=2\)

\(TH4:n+1=-3\Rightarrow n=-4\)

Vậy \(n\in\left\{0;-2;2;-4\right\}\)

Gọi a là số bé, b là số lớn, ta có:

a + b = 102 ; a0 + b = a x 10 + b = 417.

=> 10a + b - (a + b) = 315

=> 10a + b - a - b = 315 => (10a - a) + (b - b) =315

=> 9a = 315 => a=35 => b= 102 - 35 = 67.

vậy số lớn là 67 số bé là 35

\(3x+3x+1+3x+2=117\)

\(\Rightarrow3x+3x+3x=117-1-2\)

\(\Rightarrow3x+3x+3x=114\)

\(\Rightarrow x.\left(3+3+3\right)=114\)

\(\Rightarrow x.9=114\)

\(\Rightarrow x=\dfrac{38}{3}\)

Vậy \(x=\dfrac{38}{3}\)

B2:

\(25-y^2=8\left(x-2009\right)^2\)

Điều kiện:\(25-y^2\le0\)

\(\Rightarrow y\)là số lẻ

\(\Rightarrow y\in\left\{1;3;5\right\}\)

\(TH1:y=3\)

\(\Rightarrow25-1^2=24\)

\(\Rightarrow8.\left(x-2009\right)^2=24\)

\(\Rightarrow\)Ko có số nào thỏa mãn \(x\)

\(TH2:y=3\)

\(\Rightarrow25-3^2=16\)

\(\Rightarrow8.\left(x-2009\right)^2=16\)

\(\Rightarrow\)Ko số nào thỏa mãn \(x\)

\(TH3:y=5\)

\(\Rightarrow25-25=0\)

\(\Rightarrow8.\left(x-2009\right)^2=0\)

\(\Rightarrow x=2009\)

Vậy \(y=5;x=2009\)

B1:

\(-\dfrac{15}{12}x+\dfrac{3}{7}=\dfrac{6}{5}x-\dfrac{1}{2}\)

\(\Rightarrow\dfrac{3}{7}+\dfrac{1}{2}=\dfrac{6}{5}x+\dfrac{15}{12}x\)

\(\Rightarrow\dfrac{13}{14}=\dfrac{49}{20}x\)

\(\Rightarrow x=\dfrac{130}{343}\)

Vậy \(x=\dfrac{130}{343}\)