Tinh GTBT: 2x²-3y+5 tại |x|=1/2 ; |y|=1

1.  Remember to __________ the lights before going to bed.

A.   turn                 B.  turn off             C.   turn on           D.  stop

2.  It is a good idea to use __________ when travelling long distances.

A.   cars                  B.taxis                  C.   private cars    D.  public transport

3.  What should we do to __________ electricity?

A.   cut                    B.  take                 C.   save                D.  waste

4.  We shout use __________ light bulbs in our homes.

A.   low energy      B.little energy        C.   a bit energy    D.  efficient

5.  In my opinion, nuclear power is not only expensive but also _______  to

our environment.

A.   danger              B.dangerous        C.   risk                  D.  disaster

6.  Someone’s carbon _______ is a measurement of the amount of carbon

dioxide that their activities produce.

A.   effect              B.  amount            C.   footprint         D.  energy

7.  Several governments try to __________ the use of fossil fuels.

A.   reduce              B.  increase          C.   waste              D.  save

8.  We are looking for cheap, clean and _________ sources of energy.

A.   effective          B.efficient             C.   serious             D.  dangerous

9.    _______ source of energy is the source that can’t be replaced after use.

A.   Renewable        B.  Natural             C.Effective           D.  Non-renewable

0.  Wave energy is a source of _________ energy.

A. environment friendly                     C.environmentally friendly

B. environmental friendly                  D.environmentally friendliness

1,x:y:z=2:3:4 và x-y+z =-6

2,5x=3y=2z và z-x =36

x;y lần lượt tỉ lệ với 4;5 và x^2=y^2=369

|x+3/4|+1/3=1/2