a: Ta có: \(3^{2020}=3^{2018}\cdot3^2=3^{2018}\cdot9\)

mà 9<10

nên \(3^{2020}< 10\cdot3^{2018}\)

\(\frac{-11}{15}\)và  \(\frac{13}{-14}\)

\(\frac{-11}{15}\)và  \(\frac{-13}{14}\)

\(\frac{-11}{15}=\frac{-11.14}{15.14}=\frac{-154}{210}\)       ;          \(\frac{-13}{14}=\frac{-13.15}{14.15}=\frac{-195}{210}\)

Vì -154 > -195 

=> \(\frac{-154}{210}>\frac{-195}{210}\)

Vậy \(\frac{-11}{15}>\frac{-13}{14}\)

Vì 11¹³ . 11¹⁵ = 11¹⁴ . 11¹⁴ = 11²⁸ nên \(\frac{11^{13}+1}{11^{14}+1}=\frac{11^{14}+1}{11^{15}+1}\)

a) \(\dfrac{7}{12}< \dfrac{7+1}{12+1}< \dfrac{78}{13}\Rightarrow\dfrac{7}{12}< \dfrac{8}{13}\)

b) \(-4,25=-\dfrac{425}{100}=-\dfrac{17}{4}=-\dfrac{34}{8}< -\dfrac{28}{8}\Rightarrow-4,25< -\dfrac{28}{8}\)

c) \(-0,33>-0,5=-\dfrac{1}{2}=-\dfrac{19}{38}\Rightarrow-0,33>-\dfrac{19}{38}\)

d) \(\dfrac{11}{13}< \dfrac{11+2}{13+2}=\dfrac{13}{15}\Rightarrow\dfrac{11}{13}< \dfrac{13}{15}\Rightarrow-\dfrac{11}{13}>-\dfrac{13}{15}\)

a , phan bu   1-3/7=4/7

                     1-5/9=4/9        ma 4/7 lớn hơn 4/9   nên      3/7 bé hơn 5/9 (phần bù lớn hơn thì bé hơn )

b,   7/10 =14/20  

ma 14/18 > 14/20 nen 14/18 >7/10

c vi  11/10 lớn hơn 10/10 nên 11/10 lớn hơn 1

   vi 14/15<15/15 nên 14/15 bé hơn 1  suy ra   11/10 lớn hơn 14/15

ta co 45/17 = 2 11/17

vi 2 11/13 > 2 11/17 nen 2 11/13 > 45/17

a) Ta có:

\(\dfrac{16}{9}\)=\(\dfrac{48}{27}\)                 \(\dfrac{24}{13}=\dfrac{48}{26}\)

Vì 27>26

➝\(\dfrac{48}{27}>\dfrac{48}{26}hay\dfrac{16}{9}>\dfrac{24}{13}\)

So sánh:

a) 16/9 và 24/13 

 Ta có \(\dfrac{16}{9}=\dfrac{208}{117}\) và \(\dfrac{24}{13}=\) \(\dfrac{216}{117}\)

\(\Rightarrow\dfrac{216}{117}>\dfrac{208}{117}\Rightarrow\dfrac{24}{13}>\dfrac{16}{9}\)

b) 27/82 và 26/75

Ta có \(\dfrac{27}{82}\approx0,33\) và \(\dfrac{26}{75}\approx0,35\)

\(\Rightarrow9,35>0,33\Rightarrow\dfrac{26}{75}>\dfrac{27}{82}\)

a) Ta có: \(\dfrac{16}{9}=\dfrac{16\cdot13}{9\cdot13}=\dfrac{208}{117}\)

\(\dfrac{24}{13}=\dfrac{24\cdot9}{13\cdot9}=\dfrac{216}{117}\)

mà \(\dfrac{208}{117}< \dfrac{216}{117}\)

nên \(\dfrac{16}{9}< \dfrac{24}{13}\)

11¹³+1/ 11¹⁴+1 = 11¹⁴+1/11¹⁵+1

Đáp án :

a) 4/7 < 7/4

b) 13/14 > 13/15

c)11/12 > 9/10

Học tốt !!!!!!!!!!

a, <

b, >

c,>

Giải :

a) Ta thấy :

4/7 = 1 - 3/7 < 1 ( do 3/7 > 0 )

7/4  = 1 + 3/7 > 1 ( do 3/7 > 0)

=> 4/7 < 3/7

b) ta thấy :

14 < 15 

=> 13/14 > 13/15

c)Ta có :

11/12 = 55/60 > 54/60 = 9/10

=> 11/12 > 9/10

Học tốt !!!!!!!!!!