= 1/1-1/2+1/2-1/3+1/3-...-1/100
= 1 - 1/100
= 99/100
\(\frac{1}{1\cdot2}+\frac{1}{2\cdot3}+\frac{1}{3\cdot4}+...+\frac{1}{99\cdot100}\)
\(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{99}-\frac{1}{100}\)
\(=1-\frac{1}{100}\)
\(=\frac{99}{100}\)
\(\frac{1}{1}\)x[100x99-1]
\(\frac{1}{1}\)x[9900-1]
\(\frac{1}{1}\)x9989
kết quả =9989
A = 1−1/2+1/2−1/3+1/3−1/4+1/4−1/5+....+1/99−1/100
A = 1−1/100
A = 100/100−1/100
A = 99/100
