Question

[╰❥βôղɕ ɣ✼︵✰]

a)So sánh A và B, biết:A=\(\frac{2017\cdot2018-1}{2017\cdot2018}\)                           

                                      B=\(\frac{2018\cdot2019-1}{2018\cdot2019}\)

b)Cho P=\(\frac{1}{2}\)+\(\frac{1}{3}\)+\(\frac{1}{4}\)+.......+\(\frac{1}{49}\)+\(\frac{1}{50}\)và   Q=\(\frac{1}{49}\)+\(\frac{2}{48}\)+\(\frac{3}{47}\)+........+\(\frac{48}{2}\)+\(\frac{49}{1}\)Hãy tính tỉ số P và Q

Answer 1

[I don't need you]

a) ta có: \(A=\frac{2017.2018-1}{2017.2018}=\frac{2017.2018}{2017.2018}-\frac{1}{2017.2018}=1-\frac{1}{2017.2018}\)

\(B=\frac{2018.2019-1}{2018.2019}=1-\frac{1}{2018.2019}\)

\(\Rightarrow\frac{1}{2017.2018}>\frac{1}{2018.2019}\)

\(\Rightarrow1-\frac{1}{2017.2018}< 1-\frac{1}{2018.2019}\)

=> A < B

Answer 2

[Nguyễn Việt Hùng]

a)A= 2017*2018/2017*2018-1/2017*2018=1-1/2017*2018

    B = 2018*2019/2018*2019-1/2018*2019=1-1/2018*2019

vì 1/2017*2018>1/2018*2019=> A<B

b)