1.Tính :
a ) Sdfrac{1}{1.2}+dfrac{1}{2.3}+dfrac{1}{3.4}+....+dfrac{1}{2018.2019}
b ) Sdfrac{1}{1.3}+dfrac{1}{3.5}+dfrac{1}{5.7}+....+dfrac{1}{2017.2019}
c) Sdfrac{1}{2.4}+dfrac{1}{4.6}+dfrac{1}{6.8}+....+dfrac{1}{2018.2020}
d) Sdfrac{1}{1.2.3}+dfrac{1}{2.3.4}+dfrac{1}{3.4.5}+....+dfrac{1}{2017.2018.2019}
2. Tính tổng:
a) S1.2+2.3+3.4+...+2018.2019
b) S3.5+5.7+7.9+...+2017.2019
c) S2.4+4.6+6.8+...+2018.2020
d) S1.2.3+2.3.4+3.4.5+...+2017.2018.2019
3.Tính
a ) Sdfrac{1}{1.4}+dfrac{1}{4....
Đọc tiếp
1.Tính :
a ) \(S=\dfrac{1}{1.2}+\dfrac{1}{2.3}+\dfrac{1}{3.4}+....+\dfrac{1}{2018.2019}\)
b ) \(S=\dfrac{1}{1.3}+\dfrac{1}{3.5}+\dfrac{1}{5.7}+....+\dfrac{1}{2017.2019}\)
c) \(S=\dfrac{1}{2.4}+\dfrac{1}{4.6}+\dfrac{1}{6.8}+....+\dfrac{1}{2018.2020}\)
d) \(S=\dfrac{1}{1.2.3}+\dfrac{1}{2.3.4}+\dfrac{1}{3.4.5}+....+\dfrac{1}{2017.2018.2019}\)
2. Tính tổng:
a) \(S=1.2+2.3+3.4+...+2018.2019\)
b) \(S=3.5+5.7+7.9+...+2017.2019\)
c) \(S=2.4+4.6+6.8+...+2018.2020\)
d) \(S=1.2.3+2.3.4+3.4.5+...+2017.2018.2019\)
3.Tính
a ) \(S=\dfrac{1}{1.4}+\dfrac{1}{4.7}+\dfrac{1}{7.10}+.....+\dfrac{1}{2017.2020}\)
b ) \(S=\dfrac{1}{1.3.5}+\dfrac{1}{3.5.7}+\dfrac{1}{5.7.9}+....+\dfrac{1}{2017.2019.2021}\)
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