a) \(1-\frac{61}{69}=\frac{69}{69}-\frac{61}{69}=\frac{8}{69}\)

\(1-\frac{85}{93}=\frac{93}{93}-\frac{85}{93}=\frac{8}{93}\)

\(\frac{8}{69}>\frac{8}{93}\Rightarrow1-\frac{8}{69}< 1-\frac{8}{93}\)

\(\Rightarrow\frac{61}{69}< \frac{85}{93}\)

b) \(1-\frac{11}{17}=\frac{17}{17}-\frac{11}{17}=\frac{6}{17}=\frac{60}{170}\)

\(1-\frac{113}{173}=\frac{173}{173}-\frac{113}{173}=\frac{60}{173}\)

\(\frac{60}{170}>\frac{60}{173}\Rightarrow1-\frac{60}{170}< 1-\frac{60}{173}\)

\(\Rightarrow\frac{11}{17}< \frac{113}{173}\)

a ) Ta có :

\(1-\frac{41}{91}=\frac{50}{91}\) \(=\frac{500}{910}\)  ;  \(1-\frac{411}{911}=\frac{500}{911}\)

 Vì \(\frac{500}{910}>\frac{500}{911}\)nên \(\frac{41}{91}< \frac{411}{911}\)

b ) Ta có :

\(1-\frac{113}{115}=\frac{2}{115}\)   ;     \(1-\frac{93}{95}=\frac{2}{95}\)

Vì \(\frac{2}{115}< \frac{2}{95}\)nên \(\frac{113}{115}>\frac{93}{95}\).

c ) Quy đồng TS ta có :

\(\frac{13}{53}=\frac{143}{583}\) ;   \(\frac{11}{30}=\frac{143}{390}\)

Vì \(\frac{143}{583}< \frac{143}{390}\)nên   \(\frac{13}{53}< \frac{11}{30}\).

<tfh

ty

ddug 

\(A=\frac{18}{11}+\frac{11}{13}+\frac{15}{17}+\frac{17}{15}\)

\(=1+\frac{7}{11}+1-\frac{2}{13}+1-\frac{2}{17}+1+\frac{2}{15}\)

\(=4+\frac{7}{11}+\frac{2}{15}-\frac{2}{13}-\frac{2}{17}\)

\(\frac{7}{11}>\frac{2}{11}>\frac{2}{13};\frac{2}{15}>\frac{2}{17}\Rightarrow\frac{7}{11}+\frac{2}{15}>\frac{2}{11}+\frac{2}{17}\)

\(\Rightarrow\frac{7}{11}+\frac{2}{15}-\frac{2}{13}-\frac{2}{17}>0\)

\(\Rightarrow A>4+0=4\)

Vậy A>4

Vì 11/13 > 11/18 nên dễ thấy A > 18/11 + 11/18 + 15/17 + 17/15.

Mặc khác, 18/11 + 11/18 + 15/17 + 17/15 = 1 + 7/11 + 1 - 7/18 + 1 - 2/17 + 1 + 2/15

              = 4 + 7/11-7/18+2/15-2/17 > 4 (Vì 7/11 > 7/18, 2/15 > 2/17)

Vậy A > 4

c) 

\(\frac{19}{18}=1+\frac{1}{18}\)  

\(\frac{2017}{2016}=1+\frac{1}{2016}\)   

Vì \(\frac{1}{18}>\frac{1}{2016}\)  

Vậy \(\frac{19}{18}>\frac{2017}{2016}\)    

d) 

\(\frac{133}{173}=\frac{130+3}{170+3}=\frac{13+0,3}{17+0,3}\)  

Ta có : 

\(\frac{a}{b}< \frac{a+x}{b+x}\forall a;b;x>0\)  

Vậy \(\frac{13}{17}< \frac{133}{173}\)

13/21<9/11

6/17<9/25

7/12>11/-18

tk mk nha mk đang âm điểm

chúc các bn hok tốt ^-^

thank you very much