ĐKXĐ : 4 -  \(6x\)  -\(x^2\)\(\ge0\)

PT \(\left\{{}\begin{matrix}x+4\ge0\\4-6x-x^2=\left(x+4\right)^2\end{matrix}\right.\) \(\Leftrightarrow\)   \(\left\{{}\begin{matrix}x\ge-4\\x^2+7x+6=0\end{matrix}\right.\)

\(\Leftrightarrow\)\(\left\{{}\begin{matrix}x\ge-4\\\left(x+1\right)\left(x+6\right)=0\end{matrix}\right.\Rightarrow x=-1\)

Thử lại với ĐKXĐ thì thoả mãn 

Nên PT có 1 nghiệm duy nhất 

1. John cannot make a _______ to get married to Mary or stay single until he can afford a house and a car.

a. decide b. decision c. decisive d. Decisively

2. She often drives very ________ so she rarely causes accident.

a. carefully b. careful c. caring d. careless

3. All Sue’s friends and __________ came to her party.

a. relations b. relatives c. relationship d. related

4. My father studies about life and structure of plants and animals. He is a ________.

a. biology b. biologist c. biological d. biologically

5. She takes the _______ for running the household.

a. responsibility b. responsible c. responsibly d. responsiveness

6. We are a very close-nit family and very ___________ of one another.

a. supporting b. supportive c. support d. supporter

7. You are old enough to take _______ for what you have done.

a. responsible

b. responsibility c. responsibly d. irresponsible

8. He has been very interested in doing research on _______ since he was at high school.

a. biology b. biological c. biologist d. biologically

9. Although they are twins, they have almost the same appearance but they are seldom in _____.

a. agree b. agreeable c. agreement d. Agreeably

10. The more _______ and positive you look, the better you will feel.

a. confide b. confident c. confidently d. confidence

tham khảo nek 

Để ăn hết số gạo đó trong 1 ngày thì cần có số người là:
150 x 30 = 4500 (người)
Số người ăn hết trong 25 ngày là:
4500 : 20 = 225 (người)
Số người đến thêm là:
225 - 150 = 75  (người)