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\(2A=\dfrac{2^{2021}-1-1}{2^{2021}-1}=1-\dfrac{1}{2^{2021}-1}\)

\(2B=\dfrac{2^{2022}-1-1}{2^{2022}-1}=1-\dfrac{1}{2^{2022}-1}\)

mà \(2^{2021}-1< 2^{2022}-1\)

nên A<B

27 tháng 2 2022

A=22020-122021-1

⇒2A=2.(22020-1)22021-1

⇒2A=22021-222021-1

⇒2A=22021-1-122021-1

⇒2A=1-122021-1

B=22021-122022-1

⇒2B=2.(22021-1)22022-1

B/A

\(=\dfrac{1+\dfrac{2020}{2}+1+\dfrac{2019}{3}+...+1+\dfrac{1}{2021}+1}{\dfrac{1}{2}+\dfrac{1}{3}+...+\dfrac{1}{2021}+\dfrac{1}{2022}}\)

\(=\dfrac{2022\left(\dfrac{1}{2}+\dfrac{1}{3}+...+\dfrac{1}{2021}+\dfrac{1}{2022}\right)}{\dfrac{1}{2}+\dfrac{1}{3}+...+\dfrac{1}{2021}+\dfrac{1}{2022}}=2022\)

\(2.A=\frac{2^{2021}-2}{2^{2021}-1}=1-\frac{1}{2^{2021}-1}\)

\(2B=\frac{2^{2022}-2}{2^{2022}-1}=1-\frac{1}{2^{2022}-1}\)

dó \(\frac{1}{2^{2022}-1}< \frac{1}{2^{2021}-1}\Rightarrow1-\frac{1}{2^{2022}-1}>1-\frac{1}{2^{2021}-1}\Rightarrow A< B\)

HT

3 tháng 5 2023

B = \(\dfrac{1}{2002}\) + \(\dfrac{2}{2021}\) + \(\dfrac{3}{2020}\)+...+ \(\dfrac{2021}{2}\) + \(\dfrac{2022}{1}\)

B = \(\dfrac{1}{2002}\) + \(\dfrac{2}{2021}\) + \(\dfrac{3}{2020}\)+...+ \(\dfrac{2021}{2}\) + 2022

B = 1 + ( 1 + \(\dfrac{1}{2022}\)) + ( 1 + \(\dfrac{2}{2021}\)) + \(\left(1+\dfrac{3}{2020}\right)\)+ ... + \(\left(1+\dfrac{2021}{2}\right)\) 

B = \(\dfrac{2023}{2023}\) + \(\dfrac{2023}{2022}\) + \(\dfrac{2023}{2021}\) + \(\dfrac{2023}{2020}\) + ...+ \(\dfrac{2023}{2}\) 

B = 2023 \(\times\) ( \(\dfrac{1}{2023}\) + \(\dfrac{1}{2022}\) + \(\dfrac{1}{2021}\) + \(\dfrac{1}{2020}\)+ ... + \(\dfrac{1}{2}\))

Vậy B > C 

 

15 tháng 4 2023

A = \(\dfrac{2020}{2021}\) + \(\dfrac{2021}{2022}\) ;  B = \(\dfrac{2020+2021}{2021+2022}\)

B = \(\dfrac{2020+2021}{2021+2022}\)   = \(\dfrac{2020}{2021+2022}\) + \(\dfrac{2021}{2021+2022}\)

\(\dfrac{2020}{2021}\)   > \(\dfrac{2020}{2021+2022}\)

\(\dfrac{2021}{2022}\)     > \(\dfrac{2021}{2021+2022}\)

Cộng vế với vế ta có:

A = \(\dfrac{2020}{2021}\) + \(\dfrac{2021}{2022}\) > \(\dfrac{2020}{2021+2022}\) + \(\dfrac{2021}{2021+2022}\) = B

Vậy A > B

 

15 tháng 4 2023

A =  \(\dfrac{10^{10}-1}{10^{11}-1}\) 

\(\times\) 10 = \(\dfrac{(10^{10}-1)\times10}{10^{11}-1}\) = \(\dfrac{10^{11}-10}{10^{11}-1}\) = 1 - \(\dfrac{9}{10^{11}-1}\) < 1

B = \(\dfrac{10^{10}+1}{10^{11}+1}\)

\(\times\) 10 = \(\dfrac{(10^{10}+1)\times10}{10^{11}+1}\)  = \(\dfrac{10^{11}+10}{10^{11}+1}\) = 1 + \(\dfrac{9}{10^{11}+1}\) > 1

Vì 10 A< 1< 10B

Vậy A < B

 

AH
Akai Haruma
Giáo viên
29 tháng 4 2022

Lời giải:

$6A=\frac{6^{2021}+6}{6^{2021}+1}=1+\frac{5}{6^{2021}+1}>1+\frac{5}{6^{2022}+1}$
$=\frac{6^{2022}+6}{6^{2022}+1}=6.\frac{6^{2021}+1}{6^{2022}+1}=6B$

$\Rightarrow A>B$

27 tháng 3 2022

Bạn kiểm tra đề giúp mình! Bạn yêu cầu gì về giả thiết trên?

12 tháng 3 2023

tham khảo:

https://hoidap247.com/cau-hoi/3987981

12 tháng 3 2023

thứ 2 bạn thi kệ bn :v