5 B

6 A

7 B

8 C

9 D

10 C

11 B

12 D

13 B

14 D

1 . with

2 . turn on

3 . who

4 . largest

5 . preventing

6 . expect

7 . was wearing

8 . Thanks to

9 . available

10 . Don't forget to bring along a raincoat

Câu 1: 

\(\dfrac{2}{5}-\dfrac{1}{4}+\dfrac{3}{10}=\dfrac{8}{20}-\dfrac{5}{20}+\dfrac{6}{20}=\dfrac{8-5+6}{20}=\dfrac{9}{20}\) 

Câu 2:

\(\dfrac{-2}{5}:\left(1-\dfrac{1}{10}\right)=\dfrac{-2}{5}:\dfrac{9}{10}=\dfrac{-2}{5}.\dfrac{10}{9}=\dfrac{-2.10}{5.9}=\dfrac{-20}{45}=\dfrac{-4}{9}\) 

Câu 3:

\(\dfrac{7}{8}.\dfrac{4}{9}+\dfrac{1}{14}:\dfrac{5}{14}=\dfrac{7}{18}+\dfrac{1}{5}=\dfrac{53}{90}\) 

Câu 4:

\(\dfrac{2}{7}.\dfrac{3}{11}+\dfrac{2}{7}.\dfrac{8}{11}\) 

\(=\dfrac{2}{7}.\left(\dfrac{3}{11}+\dfrac{8}{11}\right)\) 

\(=\dfrac{2}{7}.1\) 

\(=\dfrac{2}{7}\)

Câu 1

\(\dfrac{2}{5}\)-\(\dfrac{1}{4}\)+\(\dfrac{3}{10}\)= \(\dfrac{8}{20}\)-\(\dfrac{5}{20}\)+\(\dfrac{6}{20}\)=\(\dfrac{3}{20}\)+\(\dfrac{6}{20}\)=\(\dfrac{9}{20}\)

Câu 2

-\(\dfrac{2}{5}\):(1-\(\dfrac{1}{10}\))= -\(\dfrac{2}{5}\):\(\dfrac{9}{10}\)=-\(\dfrac{2}{5}\).\(\dfrac{10}{9}\)=-\(\dfrac{4}{9}\)

Câu 3

\(\dfrac{7}{8}.\dfrac{4}{9}+\dfrac{1}{14}:\dfrac{5}{14}\)= \(\dfrac{7}{8}.\dfrac{4}{9}+\dfrac{1}{14}.\dfrac{14}{5}\)=\(\dfrac{7.4}{4.2.9}+\dfrac{1.14}{14.5}\)=\(\dfrac{7}{18}+\dfrac{1}{5}\)=\(\dfrac{35}{90}+\dfrac{18}{90}\)=\(\dfrac{53}{90}\)

Câu 4

\(\dfrac{2}{7}.\dfrac{3}{11}+\dfrac{2}{7}.\dfrac{8}{11}\)=\(\dfrac{2}{7}.\left(\dfrac{3}{11}+\dfrac{8}{11}\right)\)=\(\dfrac{2}{7}.1\)=\(\dfrac{2}{7}\)

5 A

6 C

7 D

8 C

9 C

10 B

11 D

12 B

13 D

14 D

5 D

6 A

7 A

8 B

9 B

10 C

11 B

12 B

13 D

14 B

1C

2D

3D

4D

5C

6D

7D

8C

9A

10A

1C

2D

3D

4C

5D

6D

7C

8A

9A

1 C

2 D

3 D

4 B

5 B

6 D

7 B

8 A

9 C

10 A

11 B

12 D

13 A

14 B

15 A

Đáp án là A

Ta có: M = 14 - 23 + (5 - 14) - (5 - 23) + 17 = 14 - 23 + 5 - 14 - 5 + 23 + 17

     = (14 - 14) + (5 - 5) - (23 - 23) + 17 = 0 + 0 - 0 + 17 = 17

N = 24 - (72 - 13 + 24) - (72 - 13) = 24 - 72 + 13 - 24 - 72 + 13

     = (24 - 24) - (72 + 72) + (13 + 13) = 0 - 144 + 26 = -118

Do đó M > N

Đáp án cần chọn là: A

Câu 1:

Phần a đề sai nên mk sửa lại:

a, x² + 5x - 14 = x² - 2x + 7x - 14 = x(x - 2) + 7(x - 2) = (x - 2)(x + 7)

b, xz + yz - 5(x + y) = z(x + y) - 5(x + y) = (x + y)(z - 5)

Câu 2:

x² - 4x = -4

\(\Leftrightarrow\) x² - 4x + 4 = 0

\(\Leftrightarrow\) (x - 2)² = 0

\(\Leftrightarrow\) x - 2 = 0

\(\Leftrightarrow\) x = 2

Vậy x = 2

Chúc bn học tốt!