a) ta có 77/99 = 7.11/9.11 = 7/9 (1)

777/999 = 7.111/9.111 = 7/9 (2) 

từ (1) , (2) => 77/99 = 777/999 = 7/9 => đpcm

b) 1313/1515 = 13.101/15.101 = 13/15 (1)

131313/151515 = 13.10101/15.10101 = 13/15 (2)

từ (1) và (2) => 1313/1515= 131313/151515 = 13/15 => đpcm

nhớ k mk nha!!

a) Ta có: \(\frac{77}{99}\)/\(\frac{11}{11}\)=\(\frac{7}{9}\), \(\frac{777}{999}\)/\(\frac{111}{111}\)=\(\frac{7}{9}\).Vì 7/9=7/9=7/9 nên 7/9=77/99=777/999. Thế là xong câu a

1717/1919 = 17.101/19.101

171717/191919 = 17.10101/19.10101

→ 17/19 = 1717/1919 = 171717/191919

Ta thay : 17/19 = 17x1/19x1

              1717/1919 = 17x101/19x101

              171717/191919 = 17x10101/19x10101

Nen 17/19 = 1717/1919 = 171717/191919.

 Nho k minh nha!

Ta thay : 17/19 = 17x1/19x1

              1717/1919 = 17x101/19x101

              171717/191919 = 17x10101/19x10101

Nen 17/19 = 1717/1919 = 171717/191919.

 Nho k minh nha!

_ \(\frac{7}{9}=\frac{7\times11}{9\times11}=\frac{7\times111}{9\times111}\Rightarrow\frac{7}{9}=\frac{77}{99}=\frac{777}{999}\)
_   \(\frac{13}{15}=\frac{13\times101}{15\times101}=\frac{13\times10101}{15\times10101}\Rightarrow\frac{13}{15}=\frac{1313}{1515}=\frac{131313}{151515}\)
_  \(\frac{20172017}{20072007}=\frac{20172017:10001}{20072007:10001}\Rightarrow\frac{20172017}{20072007}=\frac{2017}{2007}\)
_  \(\frac{123123}{456456}=\frac{123123:1001}{456456:1001}\Rightarrow\frac{123123}{456456}=\frac{123}{456}\)
~ Ủng hộ mk nha!~

1919/2323=19/23

191919/232323=19/23

19191919/23232323=19/23

Vậy 19/23=19/23=19/23=19/23

Ta co : \(\frac{15}{19};\frac{1515}{1919};\frac{151515}{191919}\)

\(\frac{1515}{1919}=\frac{15}{19}\)

\(\frac{151515}{191919}=\frac{15}{19}\)

\(\Rightarrow\frac{15}{19}=\frac{15}{19}=\frac{15}{19}\)

​                     Vậy ta chứng tỏ rằng \(\frac{15}{19}=\frac{1515}{1919}=\frac{151515}{191919}\)

a) \(\frac{5252}{7575}=\frac{52}{75};\frac{525252}{757575}=\frac{52}{75}\)

Vậy cả 3 phân số trên bằng nhau

b) \(\frac{1313}{1515}=\frac{13}{15};\frac{131313}{151515}=\frac{13}{15}\)

Vậy các phân số trên bằng nhau

\(\frac{52}{73}=\frac{52\cdot101}{73\cdot101}=\frac{5252}{7373}\)

\(\frac{52}{73}=\frac{52\cdot10101}{73\cdot10101}=\frac{525252}{737373}\)

\(\frac{13}{15}=\frac{13\cdot101}{15\cdot101}=\frac{1313}{1515}\)

\(\frac{13}{15}=\frac{13\cdot10101}{15\cdot10101}=\frac{131313}{151515}\)

a) 123/127 = 123123/127127

Ta có 123123/127127 = 123 x 1001/127 x 1001

                              <=> 123123/ 127127 = 123 /127

Vậy 123/127 = 123123 /127127

b) 13/15 = 1313/1515 = 131313/151515

- Ta có 1313/1515 = 13 x 101 / 15 x 101 

                         <=> 1313/1515 = 13/15

- ta cũng có : 131313/151515 = 13 x 10101 / 15 x10101

                                          <=> 131313/151515 = 13/15 

Vậy 13/15 = 1313/1515 = 131313 /151515

Chúc bạn học tốt <3

123/127=123123/127127=123 x 1001/127 x 1001=123/127

13/15=1313/1515=13 x 101/15 x 101=13 x 10101/15 x 10101=13/15

ung ho nhe

\(\frac{123}{127}=\frac{123123}{127127}\Rightarrow\frac{123}{127}=\frac{123.1001}{127.1001}\Rightarrow\frac{123}{127}=\frac{123}{127}\Rightarrow\frac{123}{127}=\frac{123123}{127127}\)

\(\frac{13}{15}=\frac{1313}{1515}=\frac{131313}{151515}\Rightarrow\frac{13}{15}=\frac{13.101}{15.101}=\frac{13.10101}{15.10101}\Rightarrow\frac{13}{15}=\frac{13}{15}=\frac{13}{15}\Rightarrow\frac{13}{15}=\frac{1313}{1515}=\frac{131313}{151515}\)

Ta có:

a,1313/1515=101.13/101.15=13/13.

b,123123/127127=1001.123/1001.127

=123/127.

c,20052005/20062006

=10001.2005/10001.2006

2005/2006.

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