Cho b khác c, a+b khác c và c^2+2ab-2ac-2bc=0.

RG: a^2 +(a-c)^2/b^2+(b-c)

Use the correct tense of the verbs given in the box to complete the text. '

1. earn 2. start 3. give 4.spend 5. give

6. provide 7. receive

Bill Gates, the founder of Microsoft, is one of the richest men in the world. In 2005, he(1) _________ $175 million. In 2000, his and his wife (2)__________ a charity called The Bill and Melinda Gates Foundation. So far they (3)____ about $28 billion of the fortune to the foundation. SInce 2000, the Foundation (4)__________ billions of dollars health and education. For example, in July 2000, it (5)______________ 40 million to scientists working on new ways to fight malaria. In May 2005, (6)_________ more tha $11 million for schools and collages Chicago. And since 2000, public libraries across the USA (7)_______ $ 250 million to pay for computer and internet access.

Cho đa thức f(x)=(m^2-1)x^3+(m-1)x^2-2x-1.

Tìm giá trị của hằng số m để đa thức có bậc bằng 2

So sánh:

a) -3/4 và 5/-6

b) a^2 và |-a^2|

Viết các biểu thức dưới dạng lập phương của một tổng hoặc một hiệu:

a) A = m 6 p 3   –   3 m 4 n 3 p 2   +   3 m 2 n 6 p   –   n 9 ;

b) B = x 2 + y 3 − 6 x 2 + y 2 z + 6 ( x + 2 y ) z 2 − 8 z 3 ;  

c) C = ( m   -   n ) 3   +   15 ( m   –   n ) 2 ( m   –   p )   –   75 ( n   –   m ) ( p   –   m ) 2   –   125 ( p   –   m ) 3 .

Read the following passage and mark the letter A, B, tr or I) to indicate the correct answer to each of the questions from 36 to 42.

     Humans have struggled against weeds since the beginnings of agriculture. Marring our gardens is one of the milder effects of weeds - any plants that thrive where they are unwanted. They clog waterways, destroy wildlife habitats, and impede fanning. Their spread eliminates grazing areas and accounts for one-third of all crop loss. They compete for sunlight, nutrients, and water with useful plants.

     The global need for weed control had been answered mainly by the chemical industry. Its herbicides are effective and sometimes necessary, but some pose serious problems, particularly if misused. Toxic compounds threaten animal and public health when they accumulate in food plants, groundwater, and drinking water. They also harm workers who apply them.

     In recent years, the chemical industry has introduced several herbicides that are more ecologically sound. Yet new chemicals alone cannot solve the world's weed problems. Hence, scientists are exploring the innate weed-killing powers of living organisms, primarily insects and microorganisms.

     The biological agents now in use are environmentally benign and are harmless to humans. They can be chosen for their ability to attack selected targets and leave crops and other plants untouched. In contrast, some of the most effective chemicals kill virtually all the plants they come in contact with, sparing only those that are naturally resistant or have been genetically modified for resistance. Furthermore, a number of biological agents can be administered only once, after which no added applications are needed. Chemicals typically must be used several times per growing season.

The word "marring" in bold is closest in meaning to ________.

A. spoiling

B. planting 

C. dividing

D. replacing