TÍnh nhanh:\(\dfrac{2011x1990-2011x999}{2012x999+1013}\)
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Tính nhanh:
\(\frac{2011x1999-2011x999}{2012x999+1013}\)
a)\(\frac{399x45+55x399}{1995x1996-1991x1995}\)
b)\(\frac{1995x1993-18}{1975x1993x1994}\)
c) 217x ( 63 + 26 ) - 216 x ( 63 + 26 ) - ( 63 - 26 )
d)\(\frac{2012x1999-2011x999}{2012x999+2012}\)
Tính: \(S=C^0_{2024}+\dfrac{1}{2}.C^2_{2024}+\dfrac{1}{3}.C^4_{2024}+\dfrac{1}{4}.C^6_{2024}+...+\dfrac{1}{1013}.C^{2024}_{2024}\)
Tính: \(S=C^0_{2024}+\dfrac{1}{2}.C^2_{2024}+\dfrac{1}{3}.C^4_{2024}+\dfrac{1}{4}.C^6_{2024}+...+\dfrac{1}{1013}.C^{2024}_{2024}\)
Tính: \(S=C^0_{2024}+\dfrac{1}{2}.C^2_{2024}+\dfrac{1}{3}.C^4_{2024}+\dfrac{1}{4}.C^6_{2024}+...+\dfrac{1}{1013}.C^{2024}_{2024}\)
\(S=C^0_{2024}+\dfrac{1}{2}C^2_{2024}+\dfrac{1}{3}C^4_{2024}+\dfrac{1}{4}C^6_{2024}+...+\dfrac{1}{1013}C^{2024}_{2024}\)
Ta có :
\(\dfrac{1}{k+1}C^{2k-1}_n=\dfrac{1}{k+1}.\dfrac{n!}{\left(2k-1\right)!\left(n-2k+1\right)!}\)
\(=\dfrac{1}{n+1}.\dfrac{\left(n+1\right)!}{2k!\left[\left(n+1\right)-2k\right]!}\)
\(=\dfrac{1}{n+1}C^{2k}_{n+1}\)
\(\Rightarrow S_n=\dfrac{1}{n+1}\Sigma^{2k}_{k=0}C^{2k}_{n+1}=\dfrac{1}{n+1}\left(\Sigma^{2k}_{k=0}C^{2k-1}_{n+1}-C^0_{n+1}\right)=\dfrac{2^{2n-1}-1}{n+1}\)
\(\Rightarrow S=\dfrac{2^{2025}-1}{1013}\)
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Tính: \(S=C^0_{2024}+\dfrac{1}{2}.C^2_{2024}+\dfrac{1}{3}.C^4_{2024}+\dfrac{1}{4}.C^6_{2024}+...+\dfrac{1}{1013}.C^{2024}_{2024}\)
S = C₀₂₀₂₄ + 12.C₂₀₂₄ + 13.C₂₀₂₄ + 14.C₂₀₂₄ + ... + 11013.C₂₀₂₄
= (C₀₂₀₂₄ + C₂₀₂₄ + C₂₀₂₄ + C₂₀₂₄ + ... + C₂₀₂₄) + (C₂₀₂₄ + C₂₀₂₄ + C₂₀₂₄ + ... + C₂₀₂₄) + ... + (C₂₀₂₄)
= 11014.C₂₀₂₄
= 11014.
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Tính: \(S=C^0_{2024}+\dfrac{1}{2}.C^2_{2024}+\dfrac{1}{3}.C^4_{2024}+\dfrac{1}{4}.C^6_{2024}+...+\dfrac{1}{1013}.C^{2024}_{2024}\)
Tính: \(S=C^0_{2024}+\dfrac{1}{2}.C^2_{2024}+\dfrac{1}{3}.C^4_{2024}+\dfrac{1}{4}.C^6_{2024}+...+\dfrac{1}{1013}.C^{2024}_{2024}\)
Tính: \(S=C^0_{2024}+\dfrac{1}{2}.C^2_{2024}+\dfrac{1}{3}.C^4_{2024}+\dfrac{1}{4}.C^6_{2024}+...+\dfrac{1}{1013}.C^{2024}_{2024}\)