= 1 - 1/6 + 1/6 - 1/11 + ... + 1/101 - 1/106
= 1 - 1/106
= 105/106
Ta có:\(\frac{5}{1.6}+\frac{5}{6.11}+........+\frac{5}{101.106}\)
=\(1-\frac{1}{6}+\frac{1}{6}-\frac{1}{11}+..........+\frac{1}{101}-\frac{1}{106}\)
=\(1-\frac{1}{106}\)
=\(\frac{105}{106}\)
Gọi A= 5/1.6+5/6.11+5/11.16+....+5/101.106
Ta cóA= 5-5/6 +5/6-5/11+5/11-5/16+....+5/101-5/106
Đơn giản còn lại
A= 5-5/106
=525/106
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Thấy đúng hông?
5/1.6+5/6.11+..............+5/101.106
=1-1/6+1/6-1/11 +..........+1/101.1/106
=1-1/106
=105/106
