so sánh hai số sau,A=2024x2024+2024/2024x2024+2025 và B=2024x2024+2023/2024x2024+2024
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B = \(1-\dfrac{1}{2025}\) \(A=1-\dfrac{1}{2024}\)
Vì \(\dfrac{1}{2025}< \dfrac{1}{2024}\)
Nên B>A
Ta có :
\(\dfrac{2023}{2024}\)=\(\dfrac{2024-1}{2024}\)=\(\dfrac{2024}{2024}\)-\(\dfrac{1}{2024}\)=1-\(\dfrac{1}{2024}\)
\(\dfrac{2024}{2025}\)=\(\dfrac{2025-1}{2025}\)=\(\dfrac{2025}{2025}\)-\(\dfrac{1}{2025}\)=1=\(\dfrac{1}{2025}\)
Ta thấy: \(\dfrac{1}{2024}\) lớn hơn \(\dfrac{1}{2025}\)
Nên : \(\dfrac{2023}{2024}\) lớn hơn \(\dfrac{2024}{2025}\)
⇒A lớn hơn B
\(A=2023\times2024\\ =\left(2022+1\right)\times2024\\ =2022\times2024+2024\\ B=2022\times2025\\ =2022\times\left(2024+1\right)\\ =2022\times2024+2022\)
Vì 2022 x 2024 = 2022 x 2024
=> 2024 > 2022
=> A> B
Cách 2
A= 2023 x 2024 = 4094552
B = 2022 x 2025 =4094550
Vì 4094552 > 4094550 = > A> B
\(\sqrt{2023+2025}=\sqrt{2.2024}\)
\(2\sqrt{2024}=\sqrt{4.2024}\)
\(\sqrt{2.2024}< \sqrt{4.2024}\)
=> \(\sqrt{2023+2025}< 2.\sqrt{2024}\)
\(\sqrt{2023+2025}=\sqrt{2.2024}\\ 2\sqrt{2024}=\sqrt{4.2024}\\ \sqrt{2.2024}< \sqrt{4.2024}\\ \Rightarrow\sqrt{2023+2025< 2.\sqrt{2024}}\)
a) \(2023^{2024}\) và \(2023^{2023}\)
vì 2024 > 2023 nên 20232024 > 20232023
Vậy 20232024 > 20232023
b) \(17^{2024}\) và \(18^{2024}\)
vì 17 < 18 nên 172024 < 18 2024
Vậy 172024 < 182024
\(A=\dfrac{2024^{2023}+1}{2024^{2024}+1}\)
\(2024A=\dfrac{2024^{2024}+2024}{2024^{2024}+1}=\dfrac{\left(2024^{2024}+1\right)+2023}{2024^{2024}+1}=\dfrac{2024^{2024}+1}{2024^{2024}+1}+\dfrac{2023}{2024^{2024}+1}=1+\dfrac{2023}{2024^{2024}+1}\)
\(B=\dfrac{2024^{2022}+1}{2024^{2023}+1}\)
\(2024B=\dfrac{2024^{2023}+2024}{2024^{2023}+1}=\dfrac{\left(2024^{2023}+1\right)+2023}{2024^{2023}+1}=\dfrac{2024^{2023}+1}{2024^{2023}+1}+\dfrac{2023}{2024^{2023}+1}=1+\dfrac{2023}{2024^{2023}+1}\)
Vì \(2024>2023=>2024^{2024}>2024^{2023}\)
\(=>2024^{2024}+1>2024^{2023}+1\)
\(=>\dfrac{2023}{2024^{2023}+1}>\dfrac{2023}{2024^{2024}+1}\)
\(=>A< B\)
\(#PaooNqoccc\)
a: \(B=\dfrac{154}{155+156}+\dfrac{155}{155+156}\)
\(\dfrac{154}{155}>\dfrac{154}{155+156}\)
\(\dfrac{155}{156}>\dfrac{155}{155+156}\)
=>154/155+155/156>(154+155)/(155+156)
=>A>B
b: \(C=\dfrac{2021+2022+2023}{2022+2023+2024}=\dfrac{2021}{6069}+\dfrac{2022}{6069}+\dfrac{2023}{6069}\)
2021/2022>2021/6069
2022/2023>2022/2069
2023/2024>2023/6069
=>D>C
\(A=\dfrac{2024\text{x}2024+2024}{2024\text{x}2024+2025}=1-\dfrac{1}{2024\text{x}2024+2025}\)
\(B=\dfrac{2024\text{x}2024+2023}{2024\text{x}2024+2024}=1-\dfrac{1}{2024\text{x}2024+2024}\)
\(2024\text{x}2024+2025>2024\text{x}2024+2024\)
=>\(\dfrac{1}{2024\text{x}2024+2025}< \dfrac{1}{2024\text{x}2024+2024}\)
=>\(-\dfrac{1}{2024\text{x}2024+2025}>-\dfrac{1}{2024\text{x}2024+2024}\)
=>\(-\dfrac{1}{2024\text{x}2024+2025}+1>-\dfrac{1}{2024\text{x}2024+2024}+1\)
=>A>B
A = \(\dfrac{2024\times2024+2024}{2024\times2024+2025}\)
A = \(\dfrac{2024\times2024+2024-1}{2024\times2024+2025}\)
A = \(\dfrac{2024\times2024+2024}{2024\times2024+2025}\) - \(\dfrac{1}{2024\times2024+2025}\)
A = 1 - \(\dfrac{1}{2024\times2024+2025}\)
Tương tự ta có:
B = 1 - \(\dfrac{1}{2024\times2024+2024}\)
Vì 2024 x 2024 + 2025 > 2024 x 2024 + 2024
Nên: \(\dfrac{1}{2024\times2024+2025}\) < \(\dfrac{1}{2024\times2024+2024}\)
Vậy A > B (hai phân số, phân số nào có phần bù nhỏ hơn thì phân số đó lớn hơn)