Bài 1:

\(a,\dfrac{6}{9}=\dfrac{2}{3};\dfrac{6}{24}=\dfrac{1}{4};\dfrac{48}{96}=\dfrac{1}{2};\dfrac{42}{98}=\dfrac{3}{7}\\ b,\dfrac{24}{36}=\dfrac{2}{3};\dfrac{18}{30}=\dfrac{3}{5};\dfrac{15}{120}=\dfrac{1}{8};\dfrac{80}{240}=\dfrac{1}{3}\\ c,\dfrac{5}{25}=\dfrac{1}{5};\dfrac{75}{100}=\dfrac{3}{4};\dfrac{64}{720}=\dfrac{4}{45};\dfrac{16}{1000}=\dfrac{2}{125}\)

Bài 3:

Phân số bằng \(\dfrac{3}{5}\) là:

\(\dfrac{18}{30};\dfrac{144}{240}\)

1a)2/3;1/4;1/2;3/7

b)2/3;3/5;1/8;1/3

c)1/5;3/4;4/45;2/125

3)18/30;144/240

Ex1 ko có verb à

Ex2

1 like

2 listen

3 wears

4 teaches

5 do

6 goes

7 comes

8 goes

9 watch

10 walks

11 is

12 washes

13 studies

14 wants

15 plays

16 buys

17 studies

18 tries

19 washes

20 cries

21 says

22 flies

23 don't have

1 is

2 are

3 is

4 am

5 are

6 is

7 is

8 are

8 are

10 is

11 are

12 is

13 am

14 are

15 are

2) Ta có: \(\left|4-3x\right|=\left|x+\dfrac{1}{3}\right|\)

\(\Leftrightarrow\left[{}\begin{matrix}4-3x=x+\dfrac{1}{3}\\3x-4=x+\dfrac{1}{3}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}-4x=-\dfrac{11}{3}\\2x=\dfrac{13}{3}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{11}{12}\\x=\dfrac{13}{6}\end{matrix}\right.\)

3: Ta có: \(\left|5x-2\right|-\left|3x+\dfrac{1}{2}\right|=0\)

\(\Leftrightarrow\left|5x-2\right|=\left|3x+\dfrac{1}{2}\right|\)

\(\Leftrightarrow\left[{}\begin{matrix}5x-2=3x+\dfrac{1}{2}\\5x-2=-3x-\dfrac{1}{2}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}2x=\dfrac{5}{2}\\8x=\dfrac{3}{2}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{5}{4}\\x=\dfrac{3}{16}\end{matrix}\right.\)

4: Ta có: \(\left|2x-1\right|=x+\dfrac{4}{3}\)

\(\Leftrightarrow\left[{}\begin{matrix}2x-1=x+\dfrac{4}{3}\left(x\ge\dfrac{1}{2}\right)\\1-2x=x+\dfrac{4}{3}\left(x< \dfrac{1}{2}\right)\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}2x-x=\dfrac{4}{3}+1\\-2x-x=\dfrac{4}{3}-1\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{7}{3}\\-3x=\dfrac{1}{3}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{7}{3}\\x=-\dfrac{1}{9}\end{matrix}\right.\)

\(5^{20}:\left(5^{15}.15+5^{15}.10\right)\)

\(=5^{20}:(5^{16}+5^{15}.5.2)\)

\(=5^{20}:\left(5^{16}+5^{16}.2\right)\)

\(=5^{20}:[5^{16}.(1+2)]\)

\(=5^{20}:5^{16}.3\)

\(=5^4.3\)

\(=625.3\)

\(=1875\)

- Muốn tính diện tích hình tròn, ta lấy r x 2 x 3,14 (r là bán kính hình tròn) hoặc lấy d x 3,14 (d là đường kính hình tròn)

Chúc bạn học tốt!! ^^

S=π×R^2=π×(d^2)/4

muốn tích diện tích hình tròn ta lấy 

r x r x 3,14

b1 nha mn

Câu 2: 

a: =>2/3x=1

hay x=3/2

b: =>x-1/2=2/3-3/2=4/6-9/6=-5/6

=>x=-5/6+1/2=-5/6+3/6=-2/6=-1/3

c: =>4/5x=-4/5

hay x=-1

d: =>x-3+2x+3=0

=>3x=0

hay x=0

a)Xét \(\Delta AHB\) vuông tại H và \(\Delta AHC\) vuông tại H có :

\(AB=AC\)

\(\widehat{ABC}=\widehat{ACB}\)

=> ​\(\Delta AHB\)​=\(\Delta AHC\) (ch-gn)

b) Xét \(\Delta AMH\) và \(\Delta CME\) có :

\(AM=MC\)

\(\widehat{AMH}=\widehat{CME}\)

\(ME=MH\)

=> ​\(\Delta AMH\)​=\(\Delta CME\) (c-g-c)

=> AH=CE

c)Có : \(\widehat{HAM}=\widehat{MCE}\) 

mà \(\widehat{HAM}và\widehat{MCE}\) ở vị trí so le

=> AH//CE

=> \(\widehat{AHB}=\widehat{HCE}=90^o\)

Xét  \(\Delta AHC\) và \(\Delta ECH\) có :

CH chung 

\(\widehat{AHB}=\widehat{HCE}=90^o\)

AH=CE

=> \(\Delta AHC\)=\(\Delta ECH\) (c-g-c)

=>\(\widehat{HCA}=\widehat{EHC}\)

mà \(\widehat{HCA}=\widehat{HBA}\)

=> \(\widehat{HBA}=\widehat{EHC}\)

Mà ​​​\(\widehat{HBA}và\widehat{EHC}\) ở vị trí đồng vị​

=> HM//AB