HaLinh16072008

3 tháng trước

Cho x;y;z là các số dương thỏa mãn : 1/(x+y)+1/(y+z)+1/(z+x)=6 CMR:1/(3x+3y+2z)+1/(3x+2y+3z)+1/(2x+3y+3z) ≤3/2

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Oriana008

3 tháng trước

Áp dụng BDT `1/a+1/b>=4/(a+b)` với `a;b` là các số dương, ta có :

`1/(3x+3y+2z)=1/((2x+y+z)+(x+2y+z))<=1/4(1/(2x+y+z)+1/(x+2y+z))=1/4(1/((x+y)+(x+z))+1/((x+y)+(y+z)))`

`<= 1/4[1/4(1/(x+y)+1/(x+z))+1/4(1/(x+y)+1/(y+z))]=16(2/(x+y)+1/(y+z)+1/(x+z))`

Tương tự : `1/(3x+2y+3z)<=1/16(1/(x+y)+1/(y+z)+2/(x+z))`

`1/(2x+3y+3z)<=1/16(1/(x+y)+2/(y+z)+1/(x+z))`

Cộng từng vế của BDT ta được :

`1/(3x+3y+2z)+1/(3x+2y+3z)+1/(2x+3y+3z)<=1/16(2/(x+y)+1/(y+z)+1/(x+z))+1/16(1/(x+y)+1/(y+z)+2/(x+z))+1/16(1/(x+y)+2/(y+z)+1/(x+z))=1/4(1/(x+y)+1/(y+z)+1/(z+x))=1/4 . 6=3/2` `->đpcm`

quochuylopsausau

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Cho x;y;z là các số dương thỏa mãn : 1/(x+y)+1/(y+z)+1/(z+x)=6 CMR:1/(3x+3y+2z)+1/(3x+2y+3z)+1/(2x+3y+3z) ≤3/2

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việt nam dành độc lập vào năm nào

Choose the best answer.
I think you should buy ___ pack of mineral water instead. And you can also buy _ snacks such as potato crisps, 3 kilos of mandarins, 2 kilos of apples, 3 bunches of bananas, ____ cookies and soft candies.

Choose the best answer.
We should decorate our living room with _ orange banner. We also need ____ ribbons, balloons, party hats and costume.

Choose the best answer.
I think that ______ cauliflower is not enough for 3 people. Let’s buy one more.

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Cho x;y;z là các số dương thỏa mãn : 1/(x+y)+1/(y+z)+1/(z+x)=6 CMR:1/(3x+3y+2z)+1/(3x+2y+3z)+1/(2x+3y+3z) ≤3/2

2 câu trả lời

Viết một đoạn văn hoàn chỉnh về lý do học tiếng Anh bằng cách đưa ra các manh mối ( ko chép mạng nhá)

việt nam dành độc lập vào năm nào

Choose the best answer.I think you should buy _____ pack of mineral water instead. And you can also buy _____ snacks such as potato crisps, 3 kilos of mandarins, 2 kilos of apples, 3 bunches of bananas, ______ cookies and soft candies.

Choose the best answer.We should decorate our living room with _____ orange banner. We also need ________ ribbons, balloons, party hats and costume.

Choose the best answer.I think that ______ cauliflower is not enough for 3 people. Let’s buy one more.

Đề thi - đề kiểm tra Xem thêm

Choose the best answer.
I think you should buy ___ pack of mineral water instead. And you can also buy _ snacks such as potato crisps, 3 kilos of mandarins, 2 kilos of apples, 3 bunches of bananas, ____ cookies and soft candies.

Choose the best answer.
We should decorate our living room with _ orange banner. We also need ____ ribbons, balloons, party hats and costume.

Choose the best answer.
I think that ______ cauliflower is not enough for 3 people. Let’s buy one more.