a.

- Thử với lượng nhỏ mỗi chất.

\(H_2SO_4+BaCl_2\rightarrow BaSO_4\downarrow\left(trắng\right)+2HCl\)

b. 

- Thử với lượng nhỏ mỗi chất.

\(K_2SO_4+BaCl_2\rightarrow BaSO_4\downarrow\left(trắng\right)+2KCl\)

c.

a.

- Thử với lượng nhỏ mỗi chất.

Cảm ơn anh nhiều

1 was arrested before the garden by the boy yesterday

2 his cats taken care of carefully by Jack everyday

3 Has the country been protected from Covid-19 successfully

4 is reported that the man is running out of money

is reported to be running out of money\

5 has been said that the thief got out of the prison

has been said to have got out of the prison

6 was thought that Mary had turned down the job

Mary was thought to have  turned down the job

thanhk you so much

\(1,\\ a,=\dfrac{\left(3+2\sqrt{3}\right)\sqrt{3}}{3}+\dfrac{\left(2+\sqrt{2}\right)\left(\sqrt{2}-1\right)}{1}\\ =\dfrac{3\sqrt{3}+6}{3}+\sqrt{2}=\sqrt{3}+1+\sqrt{2}\\ b,=\left(\dfrac{\sqrt{5}+\sqrt{2}}{3}-\dfrac{\sqrt{5}-\sqrt{2}}{3}+1\right)\cdot\dfrac{1}{\left(\sqrt{2}+1\right)^2}\\ =\dfrac{\sqrt{5}+\sqrt{2}-\sqrt{5}+\sqrt{2}+3}{3}\cdot\dfrac{1}{\left(\sqrt{2}+1\right)^2}\\ =\dfrac{2\sqrt{2}+3}{3\left(3+2\sqrt{2}\right)}=\dfrac{1}{3}\)

\(2,\\ A=2x+\sqrt{\left(x-3\right)^2}=2x+\left|x-3\right|\\ =2\left(-5\right)+\left|-5-3\right|=-10+8=-2\\ B=\dfrac{\sqrt{\left(2x+1\right)^2}}{\left(x-4\right)\left(x+4\right)}\left(x-4\right)^2=\dfrac{\left|2x+1\right|\left(x-4\right)}{x+4}\\ B=\dfrac{17\cdot4}{12}=\dfrac{17}{3}\)

VD1:

a: \(5\cdot\sqrt{25a^2}-25a\)

\(=5\cdot\left|5a\right|-25a\)

=-25a-25a(a<0)

=-50a

b: \(\sqrt{49a^2}+3a\)

\(=\sqrt{\left(7a\right)^2}+3a\)

=7a+3a

=10a

c: Đặt A=\(\sqrt{64a^2}-8a\)

\(=\sqrt{\left(8a\right)^2}-8a\)

=8|a|-8a

TH1: a>=0

=>A=8a-8a=0

TH2: a<0

=>A=-8a-8a=-16a

d: Đặt \(A=\sqrt{9a^6}-3a^3\)

\(=3\cdot\sqrt{a^6}-3a^3\)

\(=3\cdot\left|a^3\right|-3a^3\)

TH1: a>=0

=>\(A=3a^3-3a^3=0\)

TH2: a<0

=>\(A=-3a^3-3a^3=-6a^3\)

VD2:

a: \(4x-\sqrt{x^2-4x+4}\)

\(=4x-\sqrt{\left(x-2\right)^2}\)

=4x-|x-2|

=4x-(x-2)(x>=2)

=4x-x+2

=3x+2

b: \(3x+\sqrt{x^2+6x+9}\)

\(=3x+\sqrt{\left(x+3\right)^2}\)

=3x+|x+3|

=3x+(-x-3)(x<-3)

=2x-3

c: \(\frac{x+6\sqrt{x}+9}{x-9}\)

\(=\frac{\left(\sqrt{x}+3\right)^2}{\left(\sqrt{x}-3\right)\left(\sqrt{x}+3\right)}=\frac{\sqrt{x}+3}{\sqrt{x}-3}\)

d: \(\frac{\sqrt{x^2+4x+4}}{x+2}\)

\(=\frac{\sqrt{\left(x+2\right)^2}}{x+2}\)

\(=\frac{\left|x+2\right|}{x+2}=\pm1\)

1 My parents go shopping twice a week

2 Hoa's house has a balcony

3 My brother usually plays badminton with his friends

4 My favorite book is Tam and Cam. What is yours?

5 There are 10 pencil cases on the table

1, My parents go shopping twice a week.

2, Hoa's house has a balcony.

3, My brother usually plays badminton with his friends.

4, My favorite book is Tam and Cam. What's yours?

5, There are ten pencil cases on the table.

Em tách ra từng bài nhé !