Ta có
B=\(\left(\frac{1}{2}-1\right).\left(\frac{1}{3}-1\right).\left(\frac{1}{4}-1\right)...\left(\frac{1}{99}-1\right).\left(\frac{1}{100}-1\right)\)
\(B=\frac{1}{2}.\frac{2}{3}.\frac{3}{4}...\frac{98}{99}.\frac{99}{100}=\frac{1.2.3...99}{2.3.4...100}=\frac{1}{100}\)
\(B=\frac{1}{100}\)
le bao truc oi hinh nhu ban sai de roi phai la chia chu
Ta có
\(B=\frac{1}{2}\cdot\frac{3}{2}\cdot\frac{4}{3}\cdot\cdot\cdot\frac{99}{98}\cdot\frac{100}{99}=\frac{1\cdot3\cdot4\cdot5...99\cdot100}{2.2.3....98.99}\)
\(B=\frac{1.100}{2.2}=25\)
