a. Ta có :

x²-9= (x-3)(x+3)

=> Mtc : (x-3)(x+3)

Nhân tử phụ 1 : (x-3)(x+3):(x-3)(x+3)=1

Nhân tử phụ 2 : (x-3)(x+3):(x+3)=x-3

Qui đồng:

x+15/x²-9= x+15/(x-3)(x+3)=(x-15).1/(x-3)(x+3).1=x-15/(x-3)(x+3)

2/x+3=2.(x-3)/(x+3)(x-3)=2(x-3)/(x-3)(x+3)

        x-15/(x-3)(x+3)       +      2(x-3)/(x-3)(x+3)

  =   (x-15)+2(x-3)/(x-3)(x+3)

  =    x-15+2/x+3 

  =  x-13/x+3

b . n=36x10²³/6x10²³=6(mol)

V=6x22,4=134,4 g

a . mA= 0,5x32=16 g

5C

1B

1. Jim will pick me to the airport tomorrow

=> i will picked to the airport by Jim tomorrow

2. Peter wrote his report last week

=> his report was written by peter last week

3. They will replace the old equipment with new one

=> The old equipment will replaced with new one

a. nMg=4.8/24=0,2(mol)

nCao=5.6/56=0,1(mol)

nCa=7.4/74=0,1(mol)

b. nC0₂= 4.48/22.4=0,2(mol)

2 b

1 B

c.nSO₂=4,48:22,4=0,2

mSO₂= 0,2x64=12,8 g

d.nH₂=11,2:22,4=0,5 mol

mH₂=0,5x2=1g

nO₂=5,6:22,4=0,25 mol

mO₂=0,25x32=8g