so sánh
B=\(\dfrac{2024}{2025}\)
A=\(\dfrac{2023}{2024}\)
Giúp mình với!!!
So sánh A=\(\dfrac{2024^{2023}+1}{2024^{2024}+1}\) và B=\(\dfrac{2024^{2022}+1}{2024^{2023}+1}\)
Cám ơn các bạn!
\(A=\dfrac{2024^{2023}+1}{2024^{2024}+1}\)
\(2024A=\dfrac{2024^{2024}+2024}{2024^{2024}+1}=\dfrac{\left(2024^{2024}+1\right)+2023}{2024^{2024}+1}=\dfrac{2024^{2024}+1}{2024^{2024}+1}+\dfrac{2023}{2024^{2024}+1}=1+\dfrac{2023}{2024^{2024}+1}\)
\(B=\dfrac{2024^{2022}+1}{2024^{2023}+1}\)
\(2024B=\dfrac{2024^{2023}+2024}{2024^{2023}+1}=\dfrac{\left(2024^{2023}+1\right)+2023}{2024^{2023}+1}=\dfrac{2024^{2023}+1}{2024^{2023}+1}+\dfrac{2023}{2024^{2023}+1}=1+\dfrac{2023}{2024^{2023}+1}\)
Vì \(2024>2023=>2024^{2024}>2024^{2023}\)
\(=>2024^{2024}+1>2024^{2023}+1\)
\(=>\dfrac{2023}{2024^{2023}+1}>\dfrac{2023}{2024^{2024}+1}\)
\(=>A< B\)
\(#PaooNqoccc\)
So sánh các cặp số sau:
\dfrac{ -2024 }{ 2023 } và \dfrac{ -2023 }{ 2024 }
-2024/2023<-1
-1<-2023/2024
=>-2024/2023<-2023/2024
A = \(\dfrac{1}{3}\)-\(\dfrac{2}{^{ }3^2}\)+\(\dfrac{3}{3^3}\)-\(\dfrac{4}{3^4}\)+...+\(\dfrac{2023}{3^{2023}}\)-\(\dfrac{2024}{3^{2024}}\) so sánh A với \(\dfrac{3}{16}\)
So sánh
A = \(\dfrac{2022^{2023}+1}{2022^{2024}+1}\) và B = \(\dfrac{2022^{2022}+1}{2022^{2023}+1}\)
Trước hết ta phải chứng minh \(\dfrac{a}{b}< \dfrac{a+1}{b+1}\) (a, b ϵ N; a < b).
Thật vậy, \(\dfrac{a}{b}=\dfrac{a\left(b+1\right)}{b\left(b+1\right)}=\dfrac{a+ab}{b^2+b}\) và \(\dfrac{a+1}{b+1}=\dfrac{\left(a+1\right)b}{\left(b+1\right)b}=\dfrac{ab+b}{b^2+b}\).
Mà theo giả thuyết là a < b nên \(\dfrac{a+ab}{b^2+b}< \dfrac{ab+b}{b^2+b}\), suy ra \(\dfrac{a}{b}< \dfrac{a+1}{b+1}\) (a, b ϵ N; a < b).
Từ đây ta có:
\(B=\dfrac{2022^{2022}+1}{2022^{2023}+1}=\dfrac{2022^{2023}+2022}{2022^{2024}+2022}=\dfrac{2022^{2023}+2021+1}{2022^{2024}+2021+1}\)
Đặt \(A_1=\dfrac{2022^{2023}+2}{2022^{2024}+2}=\dfrac{2022^{2023}+1+1}{2022^{2024}+1+1}\), rõ ràng \(A_1>A\).
Đặt \(A_2=\dfrac{2022^{2023}+3}{2022^{2024}+3}=\dfrac{2022^{2023}+2+1}{2022^{2024}+2+1}\), rõ ràng \(A_2>A_1\).
...
Đặt \(A_{2020}=\dfrac{2022^{2023}+2021}{2022^{2024}+2021}=\dfrac{2022^{2023}+2020+1}{2022^{2024}+2020+1}\), rõ ràng \(A_{2020}>A_{2019}\) và \(B>A_{2020}\).
Suy ra \(B>A_{2020}>A_{2019}>...>A_2>A_1>A\). Vậy A < B.
Ta có A = \(\dfrac{2022^{2023}}{2022^{2024}}=\dfrac{1}{2022}\) ; B = \(\dfrac{2022^{2022}}{2022^{2023}}=\dfrac{1}{2022}\)
Mà \(\dfrac{1}{2022}=\dfrac{1}{2022}\)
Vậy A = B
hãy so sánh mỗi số sau
a) \(0,75^{-2,3}\) và \(0,75^{-2,4}\)
b) \(\left(\dfrac{1}{4}\right)^{2023}\) và \(\left(\dfrac{1}{4}\right)^{2024}\)
c) \(\left(3,5\right)^{2023}\) và \(\left(3,5\right)^{2024}\)
a: \(0,75< 1\)
=>Hàm số \(y=0,75^x\) nghịch biến trên R
mà -2,3>-2,4
nên \(0,75^{-2,3}< 0,75^{-2,4}\)
b: \(\dfrac{1}{4}< 1\)
=>Hàm số \(y=\left(\dfrac{1}{4}\right)^x\) nghịch biến trên R
mà 2023<2024
nên \(\left(\dfrac{1}{4}\right)^{2023}>\left(\dfrac{1}{4}\right)^{2024}\)
c: Vì 3,5>1
nên hàm số \(y=3,5^x\) đồng biến trên R
mà 2023<2024
nên \(3,5^{2023}< 3,5^{2024}\)
so sánh
\(\dfrac{10^{2023}-3}{10^{2024}-3}\)
và
\(\dfrac{10^{2022}+1}{10^{2023}+1}\)
Ta có :
\(\dfrac{10^{2023}}{10^{2024}}=\dfrac{10^{2022}}{10^{2023}}\)
mà \(\dfrac{10^{2023}}{10^{2024}}>\dfrac{10^{2023}-3}{10^{2024}-3}\)
\(\dfrac{10^{2022}}{10^{2023}}< \dfrac{10^{2022}+1}{10^{2023}+1}\)
\(\Rightarrow\dfrac{10^{2023}-3}{10^{2024}-3}< \dfrac{10^{2022}+1}{10^{2023}+1}\)
So sánh : \(A=\dfrac{8^{2021}+2}{8^{2022}+2}\) với \(B=\dfrac{8^{2023}+2}{8^{2024}+2}\)
Giúp với
\(8A=\dfrac{8^{2022}+16}{8^{2022}+2}=1+\dfrac{14}{8^{2022}+2}\)
\(8B=\dfrac{8^{2024}+16}{8^{2024}+2}=1+\dfrac{14}{8^{2024}+2}\)
Vì \(\dfrac{14}{8^{2022}+2}>\dfrac{14}{8^{2024}+2}\)
=> 8A>8B
=> A>B
2. không tính kết quả, hay so sánh:
b) M= \(\dfrac{10^{2023}+1}{10^{2024}+1}\) và N= \(\dfrac{10^{2022}+1}{10^{2023}+1}\)
b) \(M=\dfrac{10^{2023}+1}{10^{2024}+1}< 1\) ( Vì tử < mẫu )
Ta có: \(M=\dfrac{10^{2023}+1}{10^{2024}+1}< \dfrac{10^{2023}+1+9}{10^{2024}+1+9}=\dfrac{10^{2023}+10}{10^{2024}+10}=\dfrac{10.\left(10^{2022}+1\right)}{10.\left(10^{2023}+1\right)}=\dfrac{10^{2022}+1}{10^{2023}+1}=N\)
Vì \(\dfrac{10^{2023}+1}{10^{2024}+1}< \dfrac{10^{2022}+1}{10^{2023}+1}\) nên \(M< N\)
so sánh c và d : C= \(\dfrac{2^{2024}-3}{2^{2023}-1}\) và D =\(\dfrac{2^{2023}-3}{2^{2022}-1}\)
\(C=\dfrac{2^{2024}-3}{2^{2023}-1}=\dfrac{2.2^{2023}-2-1}{2^{2023}-1}=\dfrac{2\left(2^{2023}-1\right)-1}{2^{2023}-1}=2-\dfrac{1}{2^{2023}-1}\)
\(D=\dfrac{2^{2023}-3}{2^{2022}-1}=\dfrac{2.2^{2022}-2-1}{2^{2022}-1}=\dfrac{2\left(2^{2022}-1\right)-1}{2^{2022}-1}=2-\dfrac{1}{2^{2022}-1}\)
Ta có
\(2^{2023}>2^{2022}\Rightarrow2^{2023}-1>2^{2022}-1\)
\(\Rightarrow\dfrac{1}{2^{2023}-1}< \dfrac{1}{2^{2022}-1}\Rightarrow2-\dfrac{1}{2^{2023}-1}>2-\dfrac{1}{2^{2022}-1}\)
\(\Rightarrow C>D\)