a 

oki

\(a,\dfrac{199}{200}=1-\dfrac{1}{200};\dfrac{200}{201}=1-\dfrac{1}{201}\\ Vì:\dfrac{1}{200}>\dfrac{1}{201}\\ \Rightarrow1-\dfrac{1}{200}< 1-\dfrac{1}{201}\\ Vậy:\dfrac{199}{200}< \dfrac{200}{201}\\ b,\dfrac{2001}{2002}=1-\dfrac{1}{2002};\dfrac{2002}{2003}=1-\dfrac{1}{2003}\\ Vì:\dfrac{1}{2002}>\dfrac{1}{2003}\Rightarrow1-\dfrac{1}{2002}< 1-\dfrac{1}{2003}\\ Vậy:\dfrac{2001}{2002}< \dfrac{2002}{2003}\)

\(c,\dfrac{2021}{2020}=1+\dfrac{1}{2020};\dfrac{2020}{2019}=1+\dfrac{1}{2019}\\ Vì:\dfrac{1}{2020}< \dfrac{1}{2019}\\ Nên:1+\dfrac{1}{2020}< 1+\dfrac{1}{2019}\\ Vậy:\dfrac{2021}{2020}< \dfrac{2020}{2019}\\ d,\dfrac{199}{198}=1+\dfrac{1}{198};\dfrac{200}{199}=1+\dfrac{1}{199}\\ Vì:\dfrac{1}{198}>\dfrac{1}{199}\\ Nên:1+\dfrac{1}{198}>1+\dfrac{1}{199}\\ Vậy:\dfrac{199}{198}>\dfrac{200}{199}\)

Câu b thì gg search nhé

5/4 > 2021/2022

vì 5/4 >1

2021/2022<1

ta có: \(\dfrac{2021}{2022}< 1\)

          \(\dfrac{5}{4}>1\)

\(\Rightarrow\dfrac{2021}{2022}< 1< \dfrac{5}{4}\)

vậy \(\dfrac{2021}{2022}< \dfrac{5}{4}\)

a) A=6 -13 +(-14+15+16-17)+(-18+19+20-21)+...+(-2018+2019+2020-2021)+(-2022+2023+2024-2025) +2025

    A=-7 +0 +0 +...+0+0 +2025= 2018

B) 7-9+(-10+11+12-13)+(-14+15+16-17)+...+(-2018+2019+2020-2021)+2021 

B= -2+0+0+...+0+2021=2019

#Có gì không hiểu thì hỏi nha#

a/

2020.2021=(2019+1)(2022-1)=

=2019.2022-2019+2022-1=2019.2022+2>2019.2022

b/

\(4^7=\left(2^2\right)^7=2^{14}< 2^{15}\)

c/

\(199^{20}< 200^{20}=\left(8.25\right)^{20}=\left(2^3.5^2\right)^{20}=2^{60}.5^{40}\)

\(2000^{15}=\left(16.125\right)^{15}=\left(2^4.5^3\right)^{15}=2^{60}.5^{45}\)

\(\Rightarrow2000^{15}=2^{60}.5^{45}>2^{60}.5^{40}>199^{20}\)

d/

\(31^{31}< 32^{31}=\left(2^5\right)^{31}=2^{155}\)

\(17^{39}>16^{39}=\left(2^4\right)^{39}=2^{156}\)

\(\Rightarrow17^{39}=2^{156}>2^{155}>31^{31}\)

16/51<17/51=1/3<31/90

ơ bạn ơi không quy đòng mẫu số không quy đồng tử số thì làm sao so sánh được hả bạn, cái này là phân số chứ có phải số tự nhiên đâu