Giải hệ phương trình

\(\left\{{}\begin{matrix}x^3+y^3=65\\x^2y+xy^2=20\end{matrix}\right.\)

Tìm lỗi sai và sửa lỗi

1. Now that the stress of examinations are over, we can go somewhere for our holiday.

2. Tom said that he had seen John the day before but John didn't see him.

3. She has got fewer friends in her class now than  she has last year.

viết lại những câu sau mà không thay đổi nghĩa

1.I could realize how important the family is only after I left home.

=> Not until

2. I dislike it when people criticize me unfairly.

=> I object

3. Fiona was so disappointed that she could not keep on working.

=> Such

Tìm lỗi sai và sửa lại

1. Since civilization began, gold is regarded as a symbol of power and wealth.

2. I made an appointment with Dr.Raven, who considered an expert on eye disorders.

 Cho phương trình bậc hai, ẩn số là x : x² – 3x + k – 1 = 0.

Tìm giá trị của k sao cho phương trình đã cho có hai nghiệm x₁, x₂ thoả mãn  điều kiện

x₁² – x₂² = 15.

Rút gọn biểu thức

M = \(\dfrac{2}{\sqrt{7}-\sqrt{6}}-\sqrt{28}+\sqrt{54}\)

N= \(\left(2-\sqrt{3}\right)\sqrt{26+15\sqrt{3}}-\left(2+\sqrt{3}\right)\sqrt{26-15\sqrt{3}}\)

Tìm lỗi sai và sửa lại

 Children subjected to violence,exploitation,abuse and neglect are in risk of death,poor physical and mental health,HIV/ADIS infection,and educational problems

Tìm lỗi sai và sửa lại

1. So far Linda has been writing 5 novels on the problems teenagers have to cope with in the new world.

2. Although polar bears hunt other animals, they seldom rarely kill people.

3. Geogre won't lend you any money as long as you promise to pay his back.

Viết lại câu

1. Because he didn't study hard, he failed the exam.

=> Had

2. The furniture was so expensive that I couldn't buy it.

=> The furniture was