\(A=\frac{5454}{5757}-\frac{171717}{191919}=\frac{54}{57}-\frac{17}{19}=\frac{54}{57}-\frac{51}{57}=\frac{3}{57}=\frac{1}{19}\)

\(\frac{5454}{5757}-\frac{171717}{191919}=\frac{54x101}{57x101}-\frac{17x10101}{19x10101}=\frac{54}{57}-\frac{17}{19}=\frac{1}{19}\)

Môn Toán nha mọi người, mình nhầm!

\(\dfrac{5454}{5757}-\dfrac{171717}{191919}=\dfrac{1}{19}\)

\(\dfrac{2}{19}\)

Kết quả là:

 \(\frac{1}{19}\)

Ủng hộ mk nha các bn !!!

5454/5757=18/19

171717/191919=17/19

18/19-17/19=1/19

=54/57-17/19

=1/19

k nha

Có: \(\dfrac{5454}{5757}-\dfrac{171717}{191919}.\dfrac{3}{4}+\dfrac{1}{4}:x=\dfrac{2}{5}\)

=> \(\dfrac{54.101}{57.101}-\dfrac{17.10101}{19.10101}.\dfrac{3}{4}+\dfrac{1}{4}:x=\dfrac{2}{5}\)

=> \(\dfrac{18}{19}-\dfrac{17}{19}.\dfrac{3}{4}+\dfrac{1}{4}:x=\dfrac{2}{5}\)

=> \(\dfrac{21}{76}+\dfrac{1}{4}:x=\dfrac{2}{5}\)

=> \(\dfrac{1}{4}:x=\dfrac{47}{380}\)

=> x = \(\dfrac{95}{47}\)

=>18/19-17/19*3/4+1/4:x=2/5

=>1/4:x=2/5-18/19+17/19*3/4=47/380

=>x=1/4:47/380=95/47

a,2/3 * 3/4 * 4/5 * 5/6

  Giản ước 3 với 3 , 4 với 4 , 5 với 5

=>2/3 * 3/4 * 4/5 * 5/6=2/6=1/3

b,5454/5757-171717/191919

=54/57-17/19

Quy đồng:54/57-(17*3/19*3)

               =54/57-51/57

               =3/57=1/19

NHỚ CLICK ĐÚNG CHO MÌNH NHA!!!!

a,2/3 * 3/4 * 4/5 * 5/6

  Giản ước 3 với 3 , 4 với 4 , 5 với 5

=>2/3 * 3/4 * 4/5 * 5/6=2/6=1/3

b,5454/5757-171717/191919

=54/57-17/19

Quy đồng:54/57-(17*3/19*3)

               =54/57-51/57

               =3/57=1/19

a,2/3 * 3/4 * 4/5 * 5/6

  Giản ước 3 với 3 , 4 với 4 , 5 với 5

=>2/3 * 3/4 * 4/5 * 5/6=2/6=1/3

b,5454/5757-171717/191919

=54/57-17/19

Quy đồng:54/57-(17*3/19*3)

               =54/57-51/57

               =3/57=1/19

\(\dfrac{5454}{5757}-\dfrac{171717}{191919}=\dfrac{18\cdot3\cdot101}{19\cdot3\cdot101}-\dfrac{17\cdot10101}{19\cdot10101}=\dfrac{18}{19}-\dfrac{17}{19}=\dfrac{1}{19}\)

1) a) \(\frac{5454}{5757}-\frac{171717}{191919}=\frac{18\times3\times101}{19\times3\times101}-\frac{17\times10101}{19\times10101}=\frac{18}{19}-\frac{17}{19}=\frac{1}{19}\)

b) \(\frac{6}{5}\times\frac{7}{6}\times\frac{8}{7}\times....\times\frac{2021}{2020}=\frac{6\times7\times8\times...\times2021}{5\times6\times7\times...\times2020}=\frac{2021}{5}\)

2) \(\frac{1}{3}+\frac{1}{6}+\frac{1}{10}+...+\frac{1}{45}=2\times\frac{1}{6}+2\times\frac{1}{12}+2\times\frac{1}{20}+...+2\times\frac{1}{90}\)

\(=2\times\left(\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{90}\right)\)

\(=2\times\left(\frac{1}{2\times3}+\frac{1}{3\times4}+\frac{1}{4\times5}+...+\frac{1}{9\times10}\right)\)

\(=2\times\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{9}-\frac{1}{10}\right)=2\times\left(\frac{1}{2}-\frac{1}{10}\right)=2\times\frac{2}{5}=\frac{4}{5}\)

b)Vì \(a-1< a+1\)

=> \(\frac{1}{a-1}>\frac{1}{a+1}\)

1/ a x b = 1/a - 1/b 

đk : b - a = 1

\(=\dfrac{13}{17}\cdot\dfrac{17}{19}\cdot\dfrac{19}{13}=1\)

=1

1

1313/1717 = ( 1313 :101)/(1717:101)=13/17

171717/191919=(171717:10101)/(191919:10101)=17/19

231231/343343=(231231:7007)/(343343:7007)=33/49

373737/494949=(373737:10101)/(494949:10101)=37/49