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KC
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28 tháng 1 2019
Ta có: A = 1.2.3 + 2.3.4 + 3.4.5 + ... + 18.19.20
=> 4A = 4(1.2.3 + 2.3.4 + 3.4.5 + ... + 18.19.20)
=> 4A = 1.2.3.4 + 2.3.4.4 + 3.4.5.4 +...... +18.19.20.4
=> 4A = 1.2.3.4 + 2.3.4(5 - 1) + 3.4.5.(6 - 2) +..... +18.19.20.(21 - 17)
=> 4A = 1.2.3.4 + 2.3.4.5 - 2.3.4 + 3.4.5.6 - 2.3.4.5 + ..... + 17.18.19.20 - 17.18.19.20
=> 4A =18.19.20
=> 4A = 6840
=> A = 1710
28 tháng 1 2019
Đặt A=1.2.3+2.3.4+3.4.5+4.5.6+...+18.19.20
4A=(1.2.3+2.3.4+3.4.5+4.5.6+...+18.19.20)4
4A=1.2.3(4-0)+2.3.4(5-1)+3.4.5(6-2)+4.5.6(7-3)+...+18.19.20.(21-17)
4A=1.2.3.4+2.3.4.5-1.2.3.4+3.4.5.6-2.3.4.5+4.5.6.7-3.4.5.6+...+ 18.19.20.21-17.18.19.20
=>A =18.19.20.21
=>A+18.19.20.21/4
=> A=35910
3 tháng 12 2019
After each school year, to motivate their learning spirit, parents often organize for the whole family to vacation. This year, after finishing high school, he won the title of excellent student, he is very happy, rewarded him with a tour in Ha Long Bay - a beautiful sea of our country is currently voted as world cultural heritage.
I come to Ha Long with how much is eager! I heard the legend of the bay, about the dragons that make up the many islands of many shapes in the bay. Along the way, pictures of villages, houses, streets stretched out before ... Non Vietnam country so cute!
Kia Ha Long Bay! I was happy when the car parked. It is a deep blue color. Before my eyes, spread out thousands of cool sea water and small islands interwoven in the bay. Taking the boat to the bay to see the magnificent beauty of the scene here.
Standing on the deck of the boat, I heard the cool breeze blowing in my hair. Sunshine spread out to sparkling sea water. As deep in the bay as the feeling of water in the bay is a jade block but soft flexible. Looking at the vast surface is a gentle wave. In the distance, the famous Bai Chay suspension bridge looks a lovely hand waving at visitors. Going further, we are surrounded by small islands intertwined as an attractive labyrinth.
Each island has its own shape, very strange. Legend has it that there are 99 dragons dropped into the bay so that the sea water here is a blue color wonders. Each dragon has turned into an island, so this place is called Ha Long Bay. The name of each island is set in the shape that people imagine the island, which is the island, which is Con Ga island, which is Dau Go cave, ... also Ti Tomb cave, Sung Sot cave Again! Perhaps the people are so surprised about what miraculously create for Ha Long Bay. As we approach, we find 'the islands here are made up of huge limestone blocks. Through the rain and sun, they have been worn out so strange shape as today. Each island is covered by brave resilient trees: the limestone itself has very little nutrients, the tree must sk to the rock,
But to the caves to see all the strange beauty of Ha Long. Entering Sung Sot cave (perhaps because of the beauty of the cave is?), We see in the cave there are small aquifers, drops of water from the ceiling of the small cave carrying some three tiny grains of sand. These sand grains are not falling down by the water, but by embracing each other for millions of years, they form glittering stalactites. The caves here are made up of such stalactites, which are the result of an amazingly enduring natural movement. Hang very deep and wide, can hold up to thousand people. The cave floor is usually stone, while the ceiling is filled with stalactites. Stalactites also have many shapes that make visitors astound. Their common shape is cylindrical, tapering towards the end of the cave. In parular, there are places, stalactites forming meaningful images on the cave walls, ceilings. It is the couple on the wedding day, is the chicken, the monkey, ... Under the lights, the pictures that glitter wonders incredibly beautiful.
Stepping out of the cave is to set foot on the top of the island. Standing on high overlooking the vast bowl of Ha Long Bay, once again I saw around the immense blue sky in the cool pool. The small islands undulating as hugging the bay. The small boats of fishermen, the delegation of tourists gathered at the foot of the island as children are making parents ...
Leaving Ha Long Bay, I still feel surprised to enjoy the beauty of the bay - a rare wonder of the country. I feel more proud of my river bed and more absorbent than the responsibility to contribute to preserve and build the country. Your summer vacation has gone through so many interesting and rewarding things.
MJ
3 tháng 12 2019
Nowadays, Viet Nam is known as not only a potential country with flourishing market economy but also a popular travel destination with heart-touching magnificent landscapes. Recognised as one of seven new world heritage sites by UNESCO, charming scenes of Ha Long Bay seems to appeal to a large number of local and foreign tourists.
Ha Long Bay, a stunningly scenic spot is located in Quang Ninh province in the northeast of Vietnam. The bay covers an area of over 1500 sq km, includes over 1600 islands and islets which form a spectacular seascape of limestone. This is an unique heritage as it marks important events in the formation and development of Viet Nam history; simultaneously, it is also blessed by mother nature with breathtaking views. In addition,your trip to Ha Long Bay will not be complete and perfect if you miss Bo Hon island- the home of variety of flora and fauna, Yen Tu mountain, Surprise Cave or Kissing rocks. Futhermore, it enjoys warm and tropical climate which is suitable for tourists to visit at any time. Come to Ha Long, besides immersing yourselves in her natural beauty, tourists can have an opportunity to savour delicious seafood with reasonable price and best service as well as relax with water sports such as swimming, scuba-diving, water- skiing… Moreover, residents here are very amiable, hospitable and ready to help anyone if you are in a fix.
To put it briefly, a mysal, dreamy and elegant Ha Long Bay has become the pride of Vietnamese people and it is everyone’s awareness and responsibility to conserve and preserve this precious heritage.
28 tháng 6 2018
ko đúng rồi mình xin lỗi nha, đề bài là:x+y=3x-3y=2x:y
":" là dấu chia nha bạn
C
30 tháng 3 2022
1:a) 18/21 + 7 /21 = 25/21
b)12/5 - 2/1 = 12 /5 - 10/5 =2/5
c) 72 / 72 = 1
d)5/3 - 3/8 = 5/8
e) 1/27 . 4/3 = 4 / 81
6. B
7. C
#Hok Tot
C
D
k cho tui dới