Tính nhanh:
\(A=\frac{1}{2.3.4}+\frac{1}{3.4.5}+\frac{1}{4.5.6}\)
Tính nhanh: \(\frac{-1}{2.3.4}+\frac{-1}{3.4.5}+\frac{-1}{4.5.6}+...+\frac{-1}{28.29.30}\)
tính
\(\frac{1}{1.2.3}+\frac{1}{2.3.4}+\frac{1}{3.4.5}+............+\frac{1}{20.21.22}\)
Tính nhanh
1.2.3+2.3.4+3.4.5+4.5.6+...+20.21.22
tính \(\frac{1}{2.3.4}+\frac{1}{3.4.5}+\frac{1}{4.5.6}+\frac{1}{5.6.7}+\frac{1}{6.7.8}+\frac{1}{7.8.9}+\frac{1}{8.9.10}\)
Tính giá trị biểu thức :\(P=\frac{1}{1.2.3}+\frac{1}{2.3.4}+\frac{1}{4.5.6}+...+\frac{1}{98.99.100}\)
Tính nhanh
1.2 3+2.3.4+3.4.5+4.5.6+.....+20.21.22
\(\frac{1}{1.2.3}+\frac{1}{2.3.4}+\frac{1}{4.5.6}+......+\frac{1}{98.99.100}\)
\(\frac{3x}{5}=\frac{1}{1.2.3}+\frac{1}{2.3.4}+\frac{1}{3.4.5}+\frac{1}{4.5.6}+\frac{1}{5.6.7}+\frac{1}{6.7.8}\).
