Đáp án:
`Max{32/(x-2\sqrt{x-4}+10)}=32/13<=>x=5.`
Giải thích các bước giải:
`32/(x-2\sqrt{x-4}+10)(x>=4)`
`=32/(x-4-2\sqrt{x-4}+1+10+4-1)`
`=32/((\sqrt{x-4}-1)^2+13)`
Vì `(\sqrt{x-4}-1)^2>=0`
`=>(\sqrt{x-4}-1)^2+13>=13>0`
`=>32/((\sqrt{x-4}-1)^2+13)<=32/13`
Dấu "=" xảy ra khi `\sqrt{x-4}=1<=>x=5`
Vậy `Max{32/(x-2\sqrt{x-4}+10)}=32/13<=>x=5.`
Đáp án + Giải thích các bước giải:
`32/(x-2\sqrt{x-4}+10)`
`=32/(x-4-2\sqrt{x-4}+1+13)`
Với `AAx` ta có: `(\sqrt{x-4}-1)^2\ge0`
`=>(\sqrt{x-4}-1)^2+13\ge13`
`=>32/((\sqrt{x-4}-1)^2+13)\le32/13`
Dấu `=` xảy ra khi: `(\sqrt{x-4}-1)^2=0`
`=>\sqrt{x-4}-1=0`
`=>\sqrt{x-4}=1`
`=>x-4=1`
`=>x=5`
Vậy `Max` biểu thức là `32/13` khi `x=5`
việt nam có bao nhiêu vị chỉ tịch nướ c à
phân tích đa thức thành nhân tử 3x2+12x-576=0 3x bình nha
Đèn giao thông sáng màu xanh `->` vàng `->` đỏ, thời gian sáng mỗi màu lần lượt là `36;4;36s` Hỏi trong `1` ngày mỗi màu đã sáng bao nhiêu lần Làm thật logic nha ._.
Mọi ngừi ưi giúp e với ạ em cảm ưi
V. Fill each blank with a suitable word to finish the passage. Life in the countryside is a bit slower than life in the city. It isn’t as exciting as life in the city. But (1) ………………general people work hard – they work in the fields, in the garden, in the woods etc. They grow vegetables, cultivate crops and raise (2) ………………(cows, horses, buffaloes,…). Some people even have vineyards and fruits orchards.There is a ton of work to be done on the farm-milk cows, taking (3) ………………of livestock, mucking out, ploughing fields, sowing seeds, fertilizing, harvesting,…It is said that a farmer works from (4)………………to sunset. People use farm machinery and drive tractors. Children can freely play outdoors. In rural are a people (5)………………each other better. There are no skyscrapers in the countryside. People’s home may be (6) ………………a farmhouse or a cottage. People sniff air that is definitely cleaner than air in the cities. There is also (7) ………………violence and vandalism. The traffic isn’t as dense as in the cities. There (8) ………………no rush hours. Furthermore, it isn’t as noisy as it is in cities. People living in the countryside can enjoy the green scenery. They can enjoy the nature. They can (9) ………………birds chirping, deer stopping in a clearing in wood. Besides, people can eat fresh home-grown (10) ………………and fruit. It seems that life in the countryside is not that stressful. Altogether that must have a positive effect on their health. VI. Read the following passage and answer the questions below. Hi! My name is Marek. I’ve been staying in England on an exchange visit and I’ve found it a very interesting experience. I’ve been staying with a boy called Peter and his family for two weeks. The first thing I learnt was how to greet English people. When I met Peter and his parents at the airport, I tried to kiss them on the cheeks. His parents looked a bit shocked but let me kiss them. Peter just smiled and said “Hi!”. The city where they lived is very interesting, and is much bigger than my small village. I’ve never seen so many motorways, and there’s a recycling bin on every corner. It’s really noisy, though, and there are so many cars that they need to have traffic lights everywhere! I like it here but I think I still prefer the countryside. There are more trees and animals, and not so many factories. In all, I’ve learnt a lot from my exchange but I‟ll be glad to get back to Poland. I wonder what Peter will think when he comes to stay here!
Làm giúp em vs cảm ơn ạ đang gấp lắm ạ
tính toán rút gọn help thanks mọi người nha
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