1:cho f(x)=α+β.hãy xác định f(f(x))

2:cho a,b∈ R,a>0.CMR∃ y=f(x) ,x∈R. Sao cho f(f(x))=ax +b

Giúp em vs ạ ! Đang cần ạ

Diễn thế nguyên sinh có bao nhiêu đặc điểm sau đây?

I. Bắt đầu từ một môi trường chưa có sinh vật.

II. Được biến đổi tuần tự qua các quần xã trung gian.

III. Quá trình diễn thế gắn liền với sự hủy hoại môi trường.

IV. Kết quả cuối cùng thường sẽ hình thành quần xã đỉnh cực.

V. Số lượng loài tăng lên, lưới thức ăn ngày càng phức tạp

A. 2.

B. 3.

C. 4

D. 5.

may viet de ra kieu gi vay

em co oc sao ko ngi bai nao cung hoi

5.6.y=x.1.y

nhan cheo len di

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 questions from 1 to 5.

A team of Russian scientists has challenged the theory that the woolly mammoths became extinct 10,000 years ago at the end of the Ice Age. The scientists have reported that the beasts may have survived until 2000 B.C. on an island off the coast of Siberia, where researchers uncovered 29 fossilized woolly mammoth teeth ranging in age from 4,000 to 7,000 years. The question to be asked now is, how did these prehistoric pachyderms survive in their island environment? One possibility is that they adapted to their confined surroundings by decreasing their bulk. This theory is based on their smaller tooth size, which has led scientists to believe that they were only 6 feet tall at the shoulder compared with 10 feet of their full-sized counterpart. But would this be enough to enable them to survive thousands of years beyond that of other mammoths? Researchers are still working to uncover the reasons for this isolated group's belated disappearance.

The author uses the word "counterpart" in line 7 to refer to

A. mammoths with more feet

B. mammoths in an earlier time 

C. mammoths with smaller teeth

D. larger mammoths on the island