Nếu Ngọc hơn Mai 2 nhãn vỡ thì lúc đầu Ngọc hơn Mai số nhãn vở là :

                             2 + 2 = 4 ( cái )

Lúc đầu Ngọc có số nhãn vở là :

    ( 16 + 4 ) : 2 = 10 ( cái )

Lúc đầu Mai có số nhãn vở là :

16 - 10 = 6 ( cái )

Đề khó hiểu nhề !

222^555=(2.111)^555=2^555.111^555=32^111.111^555

555^222=(5.111)^222=5^222.111^222=25^111.111^222. Vì 32^111>25^111, 111^555>111^222 => 32^111.111^555>25^111.111^222=>222^555>555^222

Life in the village is simple and warm! People here legs covered their faces mud but loyal and beautiful, lasting impression. The children here do this joke sick child mice skinny, black, curly hair, bare ride runs between lunch fields. Every morning, I saw her in the village to the river carrying water, laundry, wash the rice, the farmer ... The field, rice paddy. The students go to school. The vegetables and flowers she brought to market. At noon, the farmer resting, sitting beneath a banyan tree and enlist dinner nap a few minutes. This time the students had gone home. Afternoon, I found out the first lane 1 basket she brought only a few bundles left over after selling vegetables at the market, the buffalo farmer after 1 business day. Buffalo designs ample tread it looks majestic. Children flying a kite to the kite fold, brought home and agreed to meet the next day! Every evening, the breeze through blow away the smell of rice fat fat. Oh, I love this peaceful life too, it's a far cry from one life is full of sound in the city, do not take well 1 sec quiet!

Halong Bay is one of the famous scenic country of Vietnam, has been recognized by UNESCO as world landscapes! This is the one pride of the people living on the S-shaped piece of land. To maintain and protect it 1 how long, people living nearby and tourists to know clean water. For example, when the boat cruises, visitors note not litter into the water, the people near where the fishing should not caught by mines, not catching or indiscriminate exploitation of natural resources here !

Từ cây đại hồi, người ta tách được chất hữu cơ Z dùng làm nguyên liệu cơ sở cho việc sản xuất thuốc Tamiflu – dùng phòng chống cúm gia cầm hiện nay. Khi đốt cháy hoàn toàn Z thu được CO₂ và hơi H₂O theo tỉ lệ thể tích 7 : 5. Khi phân tích Z thấy có 45,97% oxi về khối lượng. Biết khối lượng phân tử của Z không vượt quá 200 đvC. Công thức phân tử của Z là:

A. C₈H₁₄O₄

B. C₁₀H₈O₂

C. C₁₂H₃₆

D. C₇H₁₀O₅