1 I'm not really interested in robotics.

2 We might go to the moon for our summer holiday in 2050.

3 I couldn't email you last night because my computer didn't work.

4 I didn't need to finish my homework yesterday.

5 She has worked at the school canteen for two months.

6 If you don't study hard, you won't pass the exam.

Tìm từ sai hả bạn?

D C C A D C D A D B

\(\left(x^2-1\right)'=2x;\left[\left(x-2\right)^4\right]'=4\cdot\left(x-2\right)^3\cdot\left(x-2\right)'=4\left(x-2\right)^3\)

\(f''\left(x\right)=\left(x^2-1\right)'\left(x-2\right)^4+\left(x^2-1\right)\left[\left(x-2\right)^4\right]'\)

\(=2x\left(x-2\right)^4+\left(x^2-1\right)\cdot4\left(x-2\right)^3\)

\(=2\left(x-2\right)^3\left[x\left(x-2\right)+2x^2-2\right]\)

\(=2\left(x-2\right)^3\left(3x^2-2x-2\right)\)

Đặt \(f'\left(x\right)=0\)

=>\(\left[{}\begin{matrix}x=1\\x=-1\\x=2\end{matrix}\right.\)

\(f''\left(2\right)=0;f''\left(1\right)=2>0;f''\left(-1\right)=-162< 0\)

=>Chọn B 

câu 12 :A

câu 13 :B

câu 14 :D

câu 15 :A

câu 16 :D

câu 17 :A

câu 18 :C

câu cuối mik chx chắc lắm 

a: Xét ΔAFD vuông tại F và ΔCEB vuông tại E có

AD=CB

góc FAD=góc ECB

=>ΔAFD=ΔCEB

=>DF=EB

Xét tứ giác DFBE có

DF//BE

DF=BE

=>DFBE là hình bình hành

b: S CAB=S CAD

=>CH*AB=CK*AD

=>CH*AB=CK*BC

=>CH/BC=CK/AB

Xét ΔCHK và ΔBCA có

CH/BC=CK/BA

góc HCK=góc CBA

Do đó: ΔCHK đồng dạng với ΔBCA

refer

1 . Electricity will be brought to remote areas by the government next year

2 . The problem of energy shortage will be solved by using solar energy

3 . A new hydropower plant will be built to meet the increasing demand by the government

4 . In the coming decades , renewable energy will be used everyday /

5 . Will all the world's oil be used up in the next 100 years ?

6 . Solar panels will be placed on the roofs of houses to produce hot water and electricity

7 . Cold , oil , and gas won't be replaced by alternative energy sources anytime soon

8 . Will fossil fuels be completely replaced by renewable energy in the future ?

1 . Electricity will be brought to remote areas by the government next year

2 . The problem of energy shortage will be solved by using solar energy

3 . A new hydropower plant will be built to meet the increasing demand by the government

4 . In the coming decades , renewable energy will be used everyday /

5 . Will all the world's oil be used up in the next 100 years ?

6 . Solar panels will be placed on the roofs of houses to produce hot water and electricity

7 . Cold , oil , and gas won't be replaced by alternative energy sources anytime soon

8 . Will fossil fuels be completely replaced by renewable energy in the future ?