Cho số phức z thỏa mãn  z = 2 + i z + 2 1 + 2 i 1 + i = 7 + 8 i (1).Chọn đáp án sai ?

A. z là số thuần ảo

B. z có phần ảo là số nguyên tố

C. z có phần thực là số nguyên tố

D. z có tổng phần thực và phần ảo là 5

Cho số phức z thỏa mãn  z = 2 + i z + 2 1 + 2 i 1 + i = 7 + 8 i  (1).Chọn đáp án sai ?

A. z là số thuần ảo

B. z có phần ảo là số nguyên tố

C. z có phần thực là số nguyên tố

D. z có tổng phần thực và phần ảo là 5

Cho số phức z thỏa mãn: 2 + i z + 2 ( 1 + 2 i ) 1 + i = 7 + 8 i (1)

Chọn đáp án sai?

A. z là số thuần ảo

B. z có phần ảo là số nguyên tố

C. z có phần thực là số nguyên tố

D. z có tổng phần thực và phần ảo là 5

Chọn đáp án đúng:

A recent study suggests that teens’ relationship with parents, friends and teachers may have a lot to do with why they don’t get a good night’s sleep.
   David Maume, a sociologist and sleep researcher, analyzed federal health data, which interviewed 974 teenagers when they were 12, and then again at 15. He found that family dynamics have much to do with how well kids sleep. Teens, who had warm relations with their parents and felt like they could talk to them or their parents were supportive of them, tended to sleep better. However, families that were going through a divorce or a remarriage tended to affect teens’ sleep.
   And problems at school also affected teens’ sleep. Feeling safe at school and having good relations with teachers tended to promote better sleep. As did good relationships with friends. Kids who took part in sports or other positive social activities or shared similar academic goals with their friends were also more
likely to get a good night’s sleep.
  These add up to what makes lots of sense: a general feeling of well-being helps teens sleep. If we’re happy and contented, we’re much more likely to sleep better than if we’re sad and anxious.
   Now, of course, teens can hardly resist being drawn to their computers and social networking. Maume also found that when parents were strict not only about bedtime, but also about limiting technology, kids slept better. It’s a finding that seems obvious, but parents really do matter when it comes to health habits of their teenagers. Clearly, teenagers aren’t getting 9 to 10 hours a night, which puts them at risk for all the consequences of lack of sleep, including poor academic performance, colds and stress.

Question 23: What is the passage mainly about?
A. It is necessary for teens to join in sports and positive social activities.
B. Lack of adequate sleep puts teens at risk of performing poorly at school.
C. Modern technology has something to do with teens’ sleep problems.
D. Teens’ sleep is linked to their relationship with people around them.
Question 24: What does the word “them” in the passage refer to?
A. parents   B. family dynamics    C. warm relations    D. teens
Question 25: According to Maume’s analysis, who will probably have a poor night’s sleep?
A. Teens who feel like talking with their parents.
B. Teens who lack a sense of security at school.
C. Teens who have friends sharing their dreams
D. Teens who feel contented about themselves
Question 26: The word “well-being” in paragraph 4 probably means______.
A. insecurity    B. happiness    C. excitement    D. worrying
Question 27: According to the passage, which of the following is NOT TRUE?
A. Teens whose parents broke up can’t sleep well.
B. Parents can help their children sleep better by restricting their use of technology.
C. Parents have nothing to do with their children’s health habits.
D. Teens are unable to perform well at school if they don’t get sufficient sleep.