Ta có: a.bc = 115

     => a là số có ột chữ số và bc là số có hai chữ số

Mà 5 x 23 = 115

Thay vào a = 5 và bc = 23 ( thỏa mãn)

Vậy a = 5

      bc = 23

Ta có: (2x+1).(y-3) = 10 = (-10+(-1) = 2.5=1.10 và ngược lại

Nhưng để cặp số tích x . y lớn nhất thì \(\hept{\begin{cases}2x+1=1\Rightarrow x=0\\y-3=10\Rightarrow y=13\end{cases};\hept{\begin{cases}2x+1=10\Rightarrow x=\frac{9}{2}\\y-3=1\Rightarrow y=4\end{cases}}}\)

                                                           \(\hept{\begin{cases}2x+1=-1\Rightarrow x=-1\\y-3=-10\Rightarrow y=-7\end{cases};\hept{\begin{cases}2x+1=-10\Rightarrow-\frac{11}{2}\\y-3=-1\Rightarrow y=4\end{cases}}}\)

M=2+2²+2³+...+2^20.

  =(2+2²+2³+2⁴)+(2⁵+2⁶+2⁷+2⁸)+...+(2¹⁷+2¹⁸+2¹⁹+2²⁰).

  =2.(1+2+2²+2³)+2⁵.(1+2+2²+2³)+...+2¹⁷.(1+2+2²+2³).

  =2.15+2⁵+15+...+2¹⁷+15.

   =15.2.(1+2⁴+...+2¹⁶)

=3.5.2.(1+2⁴+...+2¹⁶) ^{chia hết cho 5}

I- Choose one word with different pronunciation of the underlined part. Write A, B, C or D in the space provided.

I- Choose one word with different pronunciation of the underlined part. Write A, B, C or D in the space provided.

XII. Read the following passage, then answer the questions by circling A, B, C or D.

My name is Petty and this is my husband, Phil. We both work in offices in London. We have breakfast at half past seven. We usually have bread, coffee and orange juice for breakfast. For lunch we usually have a salad or soup and sandwich. That’s at about 1.30.

We usually have dinner at half past seven in the evening. It is a big meal of the day and we have meat or fish with vegetables and potatoes or rice. We have orange juice with milk. On Saturday we often go to a restaurant for dinner at about eight o’clock.

1. Petty and her husband work in …………….

A. offices B. factories C. hospitals D. clinics

2. Petty and Phil have ………….

A. a big breakfast B. a light breakfast

C. breakfast with meat D. breakfast with eggs

3. What do they have for lunch?

A. salad and sandwich B. salad and soup

C. fish and soup D. sandwich and fish

4. What do they drink for dinner ?

A. iced tea B. iced coffee C. soda D. orange juice

5. Where do they have dinner on Saturday evenings?

A. at home B. at a hotel

C. at their friend’s house D. at a restaurant

XI. Fill in each blank with ONE suitable word.

Of all my relatives, I like my aunt Emily the (1)__________ She’s my (2) _________

youngest sister. She has never married and (3) __________alone in a small village near Bath. She’s fifty years old, (4) __________she’s quite young in spirit. She has a fair complexion, thick brown hair and dark brown eyes. She has a kind face, and when you meet (5) __________, the first thing you notice (6) __________her smile. Her face is a little wrinkled now, but I think she is still rather attractive. She is the sort of person you can always go to if you (7) _________a problem and she’s extremely generous. She likes reading (8) _________gardening, and she still goes (9) __________ long walks over the hills. I hope I’m as active as she is when I’m at her (10) __________ .

VIII. Write the correct form of the words given in capital letters

1. Lan’s classroom is on the ___________ floor. TWO

2. Mai speaks English ___________ than me. WELL

3. The Great Wall of China is the world’s ___________ structure. LONG

4. There are a lot of ___________ mountains in Viet Nam. BEAUTY

5. I’m Vietnamese. What’s your___________? NATION

6.She is very______________________ (BEAUTY)

7.It is very ______________________ in the city. (NOISE)

8.Her ______________________are small and white. (TOOTH)

9.Do you know the______________________ of this book? (WRITE)

11. Has your sister got a _____ ? She looks tired HEAD

12. This is my favorite chair. It’s so _____ COMFORT

13. Nobody in my class is _____ than Thuy GOOD

14. This tree has a lot of green _____ . LEAF

15. There are many _____ in the summer. ACT

16. Mr. Minh is always _____. BUSINESS

17. My friend is a great _____ MUSIC

18. His ambition is to be a ____ one day. MILLION