\(3,\\ a,ĐK:x\ge-5\\ PT\Leftrightarrow2\sqrt{x+5}-2\sqrt{x+5}+3\sqrt{x+5}=12\\ \Leftrightarrow\sqrt{x+5}=4\Leftrightarrow x+5=16\Leftrightarrow x=11\left(tm\right)\\ b,ĐK:x\in R\\ PT\Leftrightarrow\left|x-5\right|=6\Leftrightarrow\left[{}\begin{matrix}x-5=6\\5-x=6\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=11\\x=-1\end{matrix}\right.\)

4:

a: =>4x^4-4x^2+x^2-1=0

=>(x^2-1)(4x^2+1)=0

=>x^2-1=0

=>x=1 hoặc x=-1

b: ĐKXĐ: x<>5; x<>2

PT =>\(\dfrac{x-2}{x-5}+3=\dfrac{6}{x-2}\)

=>\(x^2-4x+4+3\left(x^2-7x+10\right)=6x-30\)

=>4x^2-25x+34-6x+30=0

=>4x^2-31x+64=0

=>\(x\in\varnothing\)

c: =>x^2(2x^2+5)+2=0

=>x^2(2x^2+5)=-2(vôlý)

d: =>(2x-5)(x-2)=3x(x-1)

=>3x^2-3x=2x^2-4x-5x+10

=>x^2+6x-10=0

=>\(x=-3\pm\sqrt{19}\)

e: ĐKXĐ: x<>3; x<>-2

PT =>x^2-3x+5=x+2

=>x^2-4x+3=0

=>(x-3)(x-1)=0

=>x=1(nhận) hoặc x=3(loại)

f: ĐKXĐ: x<>2; x<>3

PT =>2x(x-3)-5(x-2)=5

=>2x^2-6x-5x+10-5=0

=>2x^2-11x+5=0

=>2x^2-10x-x+5=0

=>(x-5)(2x-1)=0

=>x=1/2 hoặc x=5

3: Ta có: ΔABC vuông tại A 

nên \(\widehat{B}+\widehat{C}=90^0\)

hay \(\widehat{B}=60^0\)

Xét ΔABC vuông tại A có 

\(\sin\widehat{C}=\dfrac{AB}{BC}\)

\(\Leftrightarrow AB=12.5\left(cm\right)\)

\(\Leftrightarrow AC=12.5\sqrt{3}\left(cm\right)\)

5:

a: Xét tứ giác ABKC có

M là trung điểm chung của AK và BC

=>ABKC là hbh

=>góc ABK=80 độ

b: Xét ΔABK và ΔDAE có

AB=DA

góc ABK=góc DAE

BK=AE

=>ΔABK=ΔDAE

Bài 4:

\(a,\Rightarrow5⋮x\Rightarrow x\inƯ\left(5\right)=\left\{1;5\right\}\\ b,\Rightarrow x-2+7⋮x-2\\ \Rightarrow x-2\inƯ\left(7\right)=\left\{1;7\right\}\\ \Rightarrow x\in\left\{3;9\right\}\\ c,\Rightarrow3\left(x+1\right)+4⋮x+1\\ \Rightarrow x+1\inƯ\left(4\right)=\left\{1;2;4\right\}\\ \Rightarrow x\in\left\{0;1;3\right\}\\ d,\Rightarrow10x+6⋮2x-1\\ \Rightarrow5\left(2x-1\right)+11⋮2x-1\\ \Rightarrow2x-1\inƯ\left(11\right)=\left\{1;11\right\}\\ \Rightarrow x\in\left\{1;6\right\}\\ e,\Rightarrow x\left(x+3\right)+11⋮x+3\\ \Rightarrow x+3\inƯ\left(11\right)=\left\{1;11\right\}\\ \Rightarrow x=8\left(x\in N\right)\\ f,\Rightarrow x\left(x+3\right)+2\left(x+3\right)+5⋮x+3\\ \Rightarrow x+3\inƯ\left(5\right)=\left\{1;5\right\}\\ \Rightarrow x=2\left(x\in N\right)\)

D B 

fast

happy

sure

carefully

badly

because of

because

because of

because

because of

 I'm sorry that I came late 

They were disappointed that he didn't keep the secret

I'm happy that i passed the exam

We are glad that you come

he is worried that he will be punished

study

reads

will phone

make

ask

III

1 It's colder today than yesterday

2 It takes 4 hours to travel by car and fives hours by train

3 We were busier at work today than everyday

4 Jane's sister cooks worse than her

5 Nobody in this team can play football as well as Tom

IV

1 D
2 A

 Bài 2 : 

$n_{Ba(OH)_2} = 0,3(mol) ; n_{BaSO_3} = 0,08(mol)$

TH1 : $Ba(OH)_2$ dư

$Ba(OH)_2 + SO_2 \to BaSO_3 + H_2O$
$n_{SO_2} = n_{BaSO_3} = 0,08(mol)$
$V_{SO_2} = 0,08.22,4 = 1,792(lít)$

TH2 : có tạo muối axit

SO₂ + Ba(OH)₂ → BaSO₃ + H₂O

0,08......0,08..............0,08..............(mol)

2SO₂ + Ba(OH)₂ → Ba(HSO₃)₂

0,44........0,22......................................(mol)

$V_{SO_2} = (0,08 + 0,44).22,4 = 11,648(lít)$

Bài 4 : 

$n_{BaCO_3} = 0,05(mol)$

CO₂ + Ba(OH)₂ → BaCO₃ + H₂O

0,05......0,05..............0,05..............(mol)

2CO₂ + Ba(OH)₂ → Ba(HCO₃)₂

..............0,2..................0,2....................(mol)

Ba(HCO₃)₂ \(\xrightarrow{t^o}\)BaCO₃ + CO₂ + H₂O

0,2.....................0,2........................(mol)

m = 0,2.197 = 39,4 gam

4. \(n_{BaCO_3}=\dfrac{9,85}{197}=0,05\left(mol\right)\)

Bảo toàn nguyên tố Ba =>  \(n_{Ba\left(HCO_3\right)_2}=0,25-0,05=0,2\left(mol\right)\)

Lọc kết tủa đem nung thì thu được m gam chất rắn : BaCO3 

Bảo toàn nguyên tố Ba =>\(n_{BaCO_3}=n_{Ba\left(HCO_3\right)_2}=0,2\left(mol\right)\)

=> \(m=0,2.197=39,4\left(g\right)\)