Sai nha bạn

TL: 

Sai nhé bạn 

Bạn k cho mik cái đi nhé 

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HT

Sai nha

#Bonnie @Ngân Hà

PTHH : 2Al     +     6HCl  --> 2AlCl3   +    3H2 ↑   (1)

n_AlCl3 = \(\dfrac{m}{M}=\dfrac{13,35}{27+35,5.3}=0.1\left(mol\right)\) 

Từ (1) => n_HCl   =   2n_H2  = 0.2 (mol)

=> m_HCl = n.M  =  0.2 x  36.5 = 7.3 (g)

\(PTHH:2Al+6HCl\rightarrow2AlCl_3+3H_2\\ n_{AlCl_3}=\dfrac{m}{M}=\dfrac{13,35}{133,5}=0,1\left(mol\right)\\ Theo.PTHH:n_{HCl}=3.n_{AlCl_3}=3.0,1=0,3\left(mol\right)\\ m_{HCl}=n.M=0,3.36,5=10,95\left(g\right)\)

a) \(\dfrac{3}{4}+\dfrac{9}{5}\div\dfrac{3}{2}-1=\dfrac{3}{4}+\dfrac{18}{15}-1=\dfrac{39}{20}-1=\dfrac{19}{20}\)

b) \(\dfrac{6}{7}\cdot\dfrac{8}{13}+\dfrac{6}{13}\cdot\dfrac{9}{7}-\dfrac{4}{13}\cdot\dfrac{6}{7}=\dfrac{48}{91}+\dfrac{54}{91}-\dfrac{24}{91}=\dfrac{48+51-24}{91}=\dfrac{78}{91}=\dfrac{6}{7}\)

c) \(\dfrac{-3}{7}+\left(\dfrac{3}{-7}-\dfrac{3}{-5}\right)\)\(=\dfrac{-3}{7}+\left(\dfrac{-3}{7}-\dfrac{-3}{5}\right)=\dfrac{-3}{7}+\dfrac{6}{35}=-\dfrac{9}{35}\)

Chọn D

D 

D

a) \(=3\left(x-3y\right)\)

b) \(=5xy\left(3x-2y\right)\)

c) \(=5y\left(x+2y\right)+2\left(x+2y\right)=\left(x+2y\right)\left(5y+2\right)\)

d) \(=\left(9x^2+6x+1\right)-4y^2=\left(3x+1\right)^2-4y^2=\left(3x+1-2y\right)\left(3x+1+2y\right)\)

e) \(=x\left(x+1\right)+3\left(x+1\right)=\left(x+1\right)\left(x+3\right)\)

g) \(=x\left(x-2\right)-\left(x-2\right)=\left(x-2\right)\left(x-1\right)\)

a) \(3x-9y\)

\(=3\left(x-3y\right)\)

b) \(15x^2y-10xy^2\)

\(=5xy\left(3x-2y\right)\)

c) \(5xy+10y^2+2x+4y\)

\(=\left(x+2y\right)\left(5y+2\right)\)

d) \(9x^2-4x^2+6x+1\)

\(=\left(3x+1-2y\right)\left(3x+1+2y\right)\)

e) \(x^2+4x+3\)

\(=\left(x+1\right)\left(x+3\right)\)

d) \(x^2-3x+2\)

\(=\left(x-1\right)\left(x-2\right)\)

a, 3( x-3y )

b, 5xy( 3x-2y )

c, ( 5xy+ 10y^2 ) + ( 2x+4y )

= 5y( x+2y ) + 2(x+2y)

= ( x+2y )(5y+2)

d, ( 9x^2 + 6x + 1 ) - 4y^2

= ( 3x+1)^2 - 4y^2

= ( 3x+1)^2 - (2y)^2

= (3x+2y+1)(3x-2y+1)

e, x^2 +4x+4-1

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

= ( x+2)^2 - 1

= ( x+2+1)(x+2-1)

= ( x+3 ) ( x+1)

g, (x^2 -2x +1) - (x-1)

= ( x-1)^2 - (x-1)

= x-1

Câu 3

cái câu dễ thế mà ko biết đúng là gà

b: Gọi giao của AH với BC là F

=>AH vuông góc BC tại F

góic CHI=góc AHD=90 độ-góc HAD=góc ABC=1/2*sđ cung AC

góc CIH=1/2*sđ cung CA

=>góc CHI=góc CIH

=>ΔCHI cân tại C

c:

góc BDC=góc BEC=90 độ

=>BDEC nội tiếp đường tròn đường kính BC

=>MD=ME

=>ΔMDE cân tại M

mà MN là trung tuyến

nên MN vuông góc DE

Kẻ tiếp tuyến Ax của (O)

=>góc xAC=góc ABC

=>góc xAC=góc AED

=>Ax//DE

=>DE vuông góc OA

=>MN//AO

Rewrite the following sentences with the same meaning od the given ones

1. I bought a new notebook on the way to school              (stopped)

→ I stopped on the way to school to buy a new notebook.

2. We're staying in Milan for a night before flying home       (planning)

→ We're planning to stay in Milan for a night before flying home.

3. I don't want to cook tonight - let's have a takeaway           (feel)

→ I don't feel like cooking tonight - let's have a takeaway.

4. Could you ask Francis to come into my office, please ?    (mind)

→ Do you mind asking Francis to come into my office, please?

5. I don't think it's likely that you will win the competition.     (chance)

→ There is not much chance that you will win the competition.

6. They'll show Titan at the cinema and they'll release the DVD   (before)

→ They will release the DVD before showing Titan at the cinema.

7. I'll finish marking the exam and then I'll tell you your results    (soon)

→ Soon, I'll finish marking the exam and then I'll tell you your results.

8. I saw the film and then I read the book     (after)

→ After I saw the film, I read the book.

9. My parent wouldn't let me stay out lae when I was young       (used to)

→ When I was young, I used to not be allowed to stay out late by my parents.

10. Daren thinks that wearing a suit to work is appropriate     (likes)

→ Daren likes to wear a suit to work and thinks it is appropriate.