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DD
19 tháng 5 2022

b) Phương trình (1) có hai nghiệm \(x_1,x_2\) do có hệ số \(ac=1.\left(-8\right)=-8< 0\).

Theo định lí Viete ta có: 

\(\left\{{}\begin{matrix}x_1+x_2=2-m\\x_1x_2=-8\end{matrix}\right.\)

Ta có: 

\(Q=\left(x_1^2-1\right)\left(x_2^2-1\right)=x_1^2x_2^2-\left(x_1^2+x_2^2\right)+1=x_1^2x_2^2-\left(x_1+x_2\right)^2+2x_1x_2+1\)

\(=64-\left(m-2\right)^2-16+1=49-\left(m-2\right)^2\le49\)

Dấu \(=\) xảy ra khi \(m-2=0\Leftrightarrow m=2\).

Vậy \(m=2\) thỏa mãn ycbt. 

 

You should eat more vegetables, fruit, .. to be healthier.

Hok tt ha

~_Nga_~

29 tháng 1 2020

I should eat fresh vegetables, meats...(tự nghĩ thêm nha)

29 tháng 5 2023

sufficiency

4 tháng 5 2023

in the future the sun will be used as the most important __environmentally__ friendly energy sources. (environment)

17 tháng 5 2016

Cái này đâu có trog đề thi đâu bạn

3. It (9. be)…has been.….a long time since I saw Linda. So when I (10. see)…saw…...her in town yesterday, I (11. be)…was…..quite surprised. She (12. change)…changed.….a lot and (13. grow)…grew…much prettier.

4. I'm tired. We (14. walk)……have been walking….all day.

5. I'm hungry. I (15. travel)……have been travelling.for hours.

6. We are going ( 16. have) ....to have....our house (17. repaint) ..repainted.....next month.

7. I remember ( 18. take)…taking to that place once.

8. Don’t try (19. persuade) to persuade. me. Nothing can make me (20. change) change

1. about
2. from
3. with
4. to

30 tháng 11 2021

1 watchs

2 took

3 has studied

4 has been

5 have just cut

30 tháng 11 2021

1) he (watch)..... football every Sunday .

2) last week his father ( take ) .......him to the zoom.

3) I ( study)....... English for a long time ,so I speak it fluently.

4) we ( be) ........ to Dalat several times.

5) those trees (just / cut ) .......for firewood by the farmer.

Trả lời

1, watches

2, took

3, has studied

4, has been

5, have just cut

cứu em sắp đi học rồi =((Energy is fundament to human beings. Many poor people in developing countries do not have modern sources of energy like electricity or natural gas, with which their life can be improved.People who live in mountainous areas have to gather wood for fuel. This takes a lot of time. For many people living in rural areas, biogas is the largest energy resource available. The main use of biogas is for cooking and heating, but it can also provide energy for public...
Đọc tiếp

cứu em sắp đi học rồi =((
Energy is fundament to human beings. Many poor people in developing countries do not have modern sources of energy like electricity or natural gas, with which their life can be improved.

People who live in mountainous areas have to gather wood for fuel. This takes a lot of time. For many people living in rural areas, biogas is the largest energy resource available. The main use of biogas is for cooking and heating, but it can also provide energy for public transport. As biogas is smoke-free, it helps the problem of indoor air pollution. Moreover, it is made from plant waste and animal manure. They cost almost nothing.

The tendency to use renewable energy sources in developing sources in developing countries is on the increase as non-renewable ones are running out. In the future, the wind and the sun will be uses as the most important environmentally friendly energy sources.
 

True or False?

True

False

Question 58. Non-renewable sources are being used up.

 

 

Question 59. Many poor people in developing countries do not have little electricity

 

 

Question 60. Biogas is a new source of energy available for poor people.

 

 

Question 61. Biogas creates a lot of smoke.

 

 

2
21 tháng 4 2022

T

T
T

F

21 tháng 4 2022

 

True or False?

True

False

Question 58. Non-renewable sources are being used up.

 √

 

Question 59. Many poor people in developing countries do not have little electricity

 √

 

Question 60. Biogas is a new source of energy available for poor people.

 √

 

Question 61. Biogas creates a lot of smoke.

 

 √