\(\dfrac{36}{54}\) = \(\dfrac{36:18}{54:18}\) = \(\dfrac{2}{3}\)

\(\dfrac{28}{49}\) = \(\dfrac{28:7}{49:7}\) = \(\dfrac{4}{7}\)

\(\dfrac{48}{100}\) = \(\dfrac{48:4}{100:4}\) \(\dfrac{12}{25}\)

\(\dfrac{45}{81}\) = \(\dfrac{45:9}{81:9}\) = \(\dfrac{5}{9}\)

Bài 2. > , < ,  = ?

5/7 < 4/3             2/5 < 6/10            1/4 = 3/12                27/36 >

2/9           7/6 > 7/9

7/2 = 2/7        15/23 < 1                  27/9 > 2          14/15 < 1          51/17 < 4

sai rôi

a=113/13-(24/7+53/13)=113/13-24/7-53/13=60/13-24/7=396/16

b=(64/9+37/11)-44/9=64/9+37/11-44/9=20/9+37/11=181/33

c=-5/7(2/11+9/11)+15/7=-5/7+15/7=10/7

d=0.7.22/3.20.0.375.5/28=0

e=(6,17+35/9-236/97)(1/3-0.25-1/12)=A.(1/3-1/4-1/12)=A.(1/12-1/12)=A.0=0

e=(6,17 + 3 5/9 - 2 36/97 ) . ( 1/3 - 0,25 - 1/12)=(6,17 + 3 5/9 - 2 36/97 ) .(1/3-1/12-0,25)

=(6,17 + 3 5/9 - 2 36/97 ) .(4/12-1/12-0,25)=(6,17 + 3 5/9 - 2 36/97 ) .(3/12-0,25)

=(6,17 + 3 5/9 - 2 36/97 ) .(1/4-0.25)=(6,17 + 3 5/9 - 2 36/97 ) .(0.25-0.25)

=(6,17 + 3 5/9 - 2 36/97 ) .0=0

Vậy E=0

Bài 2 : a, x = -36/9 = -4

b, đề sai 

c, <=> -2 =< x =< -3 => x = -1 

Bài 1: 

a: 2/8=9/36; 2/9=8/36; 8/2=36/9; 9/2=36/8

b: -2/4=9/-18; -2/9=4/-18; 4/-2=-18/9; 9/-2=-18/4

Bài 2: 

a: =>x/3=-4/3

hay x=-4

Câu b đề sai rồi bạn

bạn nào bít giúp mìn với dang can gap lam lam lam ai giup duoc thi thank nhiu

tính mt ý bn ...nhanh mak !

a) x/49 = -3/7

x/49=-21/7

=>x=-21

b)x-2/12=2/3

x-2/12=8/12

=>x-2=8

x=8+2

x=10

\(B=\frac{2}{3.5}+\frac{2}{5.7}+\frac{2}{7.9}+...+\frac{2}{41.43}\)

\(=\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+...+\frac{1}{41}-\frac{1}{43}\)

\(=\frac{1}{3}-\frac{1}{43}\)

\(=\frac{40}{129}\)

p/s: chúc bạn học tốt

7 x 8 = 56       16 : 2 = 8       36 : 6 = 6       49 : 7 = 7

2 x 5 = 10       72 : 8 = 9       9 x 3 = 27       63 : 7 = 9

6 x 4 = 24       25 : 5 = 5       4 x 8 = 32       7 x 5 = 35

7 x 8 = 56

2 x 5 = 10

6 x 4 = 24

16 : 2 = 8 

72 : 8 = 9

25 : 5 = 5

36 : 6 = 6

9 x 3 = 27

4 x 8 = 32

49 : 7 = 7

63 : 7 = 9

7 x 5 = 35

a)\(\left(5x+1\right)^2=\frac{36}{49}\\ \left(5x+1\right)^2=\left(\frac{6}{7}\right)^2\\ \Rightarrow\left[{}\begin{matrix}5x+1=\frac{6}{7}\\5x+1=\frac{-6}{7}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=\frac{-1}{35}\\x=\frac{-13}{35}\end{matrix}\right.\)

vậy...

2.

a) \(\left(5x+1\right)^2=\frac{36}{49}\)

⇒ \(5x+1=\pm\frac{6}{7}\)

⇒ \(\left[{}\begin{matrix}5x+1=\frac{6}{7}\\5x+1=-\frac{6}{7}\end{matrix}\right.\) ⇒ \(\left[{}\begin{matrix}5x=\frac{6}{7}-1=-\frac{1}{7}\\5x=\left(-\frac{6}{7}\right)-1=-\frac{13}{7}\end{matrix}\right.\) ⇒ \(\left[{}\begin{matrix}x=\left(-\frac{1}{7}\right):5\\x=\left(-\frac{13}{7}\right):5\end{matrix}\right.\)

⇒ \(\left[{}\begin{matrix}x=-\frac{1}{35}\\x=-\frac{13}{35}\end{matrix}\right.\)

Vậy \(x\in\left\{-\frac{1}{35};-\frac{13}{35}\right\}.\)

Chúc bạn học tốt!