766,28-428,94=337,34

Lời giải:

$765,28-327,94=437,34$

7A

8C

9D

10A

11C

12C

13B

14B

B - D - C - D - A - B - C - C - A - A 

( 125 x 0,75 + 125 x 25% ) x ( 9 x 11 - 0,9 x100 - 0,9 x10)

=( 125 x 0,75 + 125 x 25% ) x          0

=          0

xuống

a: Để A là số nguyên thì \(2n-3\in\left\{1;-1\right\}\)

hay \(n\in\left\{2;1\right\}\)

\(a,A=\dfrac{-3\left(2n-3\right)-8}{2n-3}=-3-\dfrac{8}{2n-3}\in Z\\ \Leftrightarrow2n-3\inƯ\left(8\right)=\left\{-1;1\right\}\left(2n-3\text{ lẻ}\right)\\ \Leftrightarrow n\in\left\{1;2\right\}\)

\(b,\dfrac{ab}{a+2b}=\dfrac{3}{2}\Leftrightarrow\dfrac{a+2b}{ab}=\dfrac{1}{b}+\dfrac{2}{a}=\dfrac{2}{3}\\ \dfrac{bc}{b+2c}=\dfrac{4}{3}\Leftrightarrow\dfrac{b+2c}{bc}=\dfrac{1}{c}+\dfrac{2}{b}=\dfrac{3}{4}\\ \dfrac{ca}{c+2a}=3\Leftrightarrow\dfrac{c+2a}{ca}=\dfrac{1}{a}+\dfrac{2}{c}=\dfrac{1}{3}\)

Cộng vế theo vế \(\Leftrightarrow\dfrac{3}{a}+\dfrac{3}{b}+\dfrac{3}{c}=\dfrac{2}{3}+\dfrac{3}{4}+\dfrac{1}{3}=\dfrac{7}{4}\)

\(\Leftrightarrow3\left(\dfrac{1}{a}+\dfrac{1}{b}+\dfrac{1}{c}\right)=\dfrac{7}{4}\\ \Leftrightarrow\dfrac{ab+bc+ca}{abc}=\dfrac{7}{12}\\ \Leftrightarrow T=\dfrac{abc}{ab+bc+ca}=\dfrac{12}{7}\)

1 D

2 B

3 A

4 A

5 D

6 A

7 B

8 C

9 A

10 D

11 D

12 D

13 A

14 A

15 D

16 C

17 C

18 D

19 A

20 A

21 D

23 A

23 B

24 A

25 C

26 A

27 C

28 B

29 A

30 D

31 B

39 D

33 C

34 A

35 A

36 A

37 B

38 D

(2/3-3/4)^2 x 12/7-5/7  = -15/49

nha bạn chúc bạn học tốt nha 

\(=\dfrac{32}{15}\cdot\dfrac{9}{17}\cdot\dfrac{3}{32}\cdot\dfrac{-17}{3}=-\dfrac{9}{3}=-3\)

=(22/15.3/32)   .   (9/17  :  -3/17)

=66/480     .     (-3)

=11/80  . (-3)

=-33/80

She left the note on the door because the house is empty

Since Lan was careless, she lost the game