a chia hết cho b nên b = 18.

Mà BCNN = 360 chia hết cho a và b mà a chia hết cho b nên a = 360.

Like most people, I turn on my laptop play -> to play as well as to study. At weekend, I go to my favourite chat rooms and I chat. Sometimes I spend hours online and I often make new friends. My mum doesn't go shop -> shopping anymore. She likes buy -> buying everything online. My sister likes music and she has join -> joined a rock group which she found on a webpage at her university. When I want to improving -> improve my English, there are a lot of great websites with vocabulary games and practice exercises. I usually score more points than my sister !

phân tích các đa thức sau thành nhân tử
a) x^2 + 2x + 1

\(=\left(x+1\right)^2\)
b) x^2 + 6x + 9

\(=\left(x+3\right)^2\)
c) x^2 - 6x + 9

\(=\left(x-3\right)^2\)
d) x^2 - 2x + 1

\(=\left(x-1\right)^2\)
e ) 4x^2 + 4xy +y^2

\(=\left(2x\right)^2+4xy+y^2\)

\(=\left(2x+y\right)^2\)
f) x^2 + 4xy + 4y^2

\(=x^2+4xy+\left(2y\right)^2\)

\(=\left(x+2y\right)^2\)

p/s: --.--

   7⁶ + 7⁵ - 7⁴ = 7⁴ . ( 7² + 7¹- 1)

                    = 7⁴ . (49 + 7 - 1)

                    =7⁴ . 55

Vi 55 chi het cho 11 nen 7⁴ .  55 chia het cho 11

 Vay 7⁶ +7⁵ - 7⁴ chia het cho 11

Put the correct verbs:

1. After Nick (do) had done homework, he (go)went to bed last night

2. Mai ( live ) had lived in Hai Phong for 5 years before she ( move) moved to Ha Noi 3 years ago.

3. Phong (tell) told yesterday that he (learn)had learnt French for a years

4. Ms Hong (work)had worked at our school for 20 years before she (retive)retired last June

5. By the time I (get) got to Nick's house, his party had already started (already started)

6. When we (come) came back to our home village last month, it (change)had changed so much

7. I couldn't recognize my cousin because he (grow) had grown a lot

8. By the time the bus (come)came this morning, Duong (wait)had waited for it half an hours

9. Most people (leave)had left before the volcano (erupt) eruption

10. I (find)found find my pen after I (buy)bought a new one.

1. She was ____extremely______ tired after the journey. ( extreme )

2. In summer, there is usually a ____shortage______ of electricity. ( short )

3.The most ____disastrous_____ earthquake in Japanese history damged Tokyo and Yokohama and killed about 150.000 people. ( disaster )

4. We were diasspointed because of his _____behaviour_____ ( behave )

5.My father can repair electrical ___appliances______ very well. ( apply )

6.Peple often say ___tidal____ waves are the result of an abrupt ship in the under water movement of the earth. ( tide )

7. They have found out the ___solution____ abotu the pollution. ( solve )

8. There is a great ____similarity_____ between Harry and his twin brother. ( similar )