Đào nhiều tuổi nhất .Đào nhiều hơn tùng 7 tuổi

66 x 25 +5 x 66+66 x 14 + 33 x 66

= 66 x ( 25+5+14+33)

= 66 x 77

= 11 x 6 x 11 x 7

= 11 x( 6x 7)

 = 11 x 42

= 462

tick cho mình nha,Mạnh Dũng

ab3 = ab + 288

ab . 10 + 3 = ab + 288

ab.10 - ab + 3 = 288 

ab . 9 + 3 = 288 

ab . 9 = 288 - 3

ab . 9 = 285

ab = 285 : 9

ab = ?

\(Vì\dfrac{1}{2^2}< \dfrac{1}{1.2};\dfrac{1}{3^2}< \dfrac{1}{2.3};.....;\dfrac{1}{n^2}< \dfrac{1}{(n-1).n}\)

\(\Rightarrow\dfrac{1}{2^2}+\dfrac{1}{3^2}+\dfrac{1}{4^2}+....+\dfrac{1}{n^2}< \dfrac{1}{1.2}+\dfrac{1}{2.3}+....+\dfrac{1}{\left(n-1\right).1}< 1\)\(\Rightarrow\dfrac{1}{2^2}+\dfrac{1}{3^2}+\dfrac{1}{4^2}+....+\dfrac{1}{n^2}< 1\left(đpcm\right)\)

vậy \(\dfrac{1}{2^2}+\dfrac{1}{3^2}+\dfrac{1}{4^2}+....+\dfrac{1}{n^2}< 1\)

(A=dfrac{2.3}{2.4}+dfrac{2.3}{4.6}+dfrac{2.3}{6.8}+dfrac{2.3}{8.10}+....+dfrac{2.3}{30.32}+dfrac{2.3}{32.34})(A=3(dfrac{2}{2.4}+dfrac{2}{4.6}+dfrac{2}{6.8}+dfrac{2}{8.10}+....+dfrac{2}{30.32}+dfrac{2}{32.34}))

(A=3(dfrac{1}{2}-dfrac{1}{4}+dfrac{1}{4}-dfrac{1}{6}+dfrac{1}{6}-dfrac{1}{8}+dfrac{1}{8}-dfrac{1}{10}+....+dfrac{1}{30}-dfrac{1}{32}+dfrac{1}{32}-dfrac{1}{34}))

(A=3(dfrac{1}{2}-dfrac{1}{32}))

(A=3(dfrac{16}{32}-dfrac{1}{32}))

(A=3.dfrac{15}{32})

(A=dfrac{45}{32})

Vậy (A=dfrac{45}{32})

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the following questions.

Long ago prehistoric man began to domesticate a number of wild plants and animals for his own use. This not only provided a more abundant food source but also allowed more people to live on a smaller plot of ground. We tend to forget that all of our present-day pets, livestock, and food plants were taken from the wild and developed into the forms we know today.

As centuries passed and human cultures evolved and blossomed, humans began to organise their knowledge of nature into the broad field of natural history. One aspect of early natural history concerned the use of plants for drugs and medicine. The early herbalists sometimes overworked their imaginations in this respect. For example, it was widely believed that a plant or part of a plant that resembles an internal organ would cure ailments of that organ. Thus, an extract made from a heartshaped leaf might be prescribed for a person suffering from heart problems.

Nevertheless, the overall contributions of these early observers provided the rudiments of our present knowledge of drugs and their uses.

Domestication of plants and animals probably occurred because of________.

A. the need for more readily available food

B. lack of wild animals and plant

C. early man's power as a hunter

D. the desire of prehistoric man to be nomadic

Để điều chế 1 lít dung dịch ancol etylic 46^o cần dùng m gam glucozơ (khối lượng riêng của ancol etylic nguyên chất là 0,8 gam/ml). Biết hiệu suất phản ứng là 80%. Giá trị của m là

A. 900

B. 720

C. 1800

D. 90