Question

a) tìm x :\(\dfrac{2}{1.4}x+\dfrac{2}{4.7}x+\dfrac{2}{7.10}x+....+\dfrac{2}{31.344}x=10\)

b)so sánh hai phân số sau : A=\(\dfrac{6^{2020}+1}{6^{2021}+1}\)và B=\(\dfrac{6^{\text{2021}}+1}{\text{6}^{\text{2022}}+1}\)

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Answer 1

a: =>x*2/3(1-1/4+1/4-1/7+...+1/31-1/34)=10

=>2/3x*33/34=10

=>1/17x=10

=>x=170

b: \(6A=\dfrac{6^{2021}+1+5}{6^{2021}+1}=1+\dfrac{5}{6^{2021}+1}\)

\(6B=\dfrac{6^{2022}+6}{6^{2022}+1}=1+\dfrac{5}{6^{2022}+1}\)

6^2021<6^2022

=>A>B