Tìm x biết: \(\frac{1}{5X8}+\frac{1}{8X11}+\frac{1}{11X14}+.....+\frac{1}{xX\left(x+3\right)}=\frac{101}{1540}\)
Tính tông A biết : $\frac{1}{5x8}+\frac{1}{8x11}+\frac{1}{11x14}+...+$
Tính nhanh:
P = \(\frac{1}{5x8}+\frac{1}{8x11}+\frac{1}{11x14}+..........+\frac{1}{602x605}\)
Q = \(\frac{4}{3x7}+\frac{5}{7x12}+\frac{1}{12x13}+\frac{7}{13x20}+\frac{3}{20x23}\)
R = \(\left(1-\frac{1}{15}\right)\times\left(1-\frac{1}{21}\right)\times\left(1-\frac{1}{28}\right)\times........\times\left(1-\frac{1}{210}\right)\)
\(\frac{1}{2x5}+\frac{1}{5x8}+\frac{1}{8x11}+\frac{1}{11x14}+\frac{1}{14x17}+\frac{1}{17x20}\)
Tính B = \(\frac{3}{2x5}+\frac{3}{5x8}+\frac{3}{8x11}+\frac{3}{11x14}\)
\(\frac{2}{5x8}+\frac{2}{8x11}+\frac{2}{11x14}+...+\frac{2}{95x98}\)
\(\frac{2}{5x8}+\frac{2}{8x11}+\frac{2}{11x14}+...+\frac{2}{95x98}\)
Chứng Minh: \(\frac{2}{2x5}\)+\(\frac{2}{5x8}\)+\(\frac{2}{8x11}\)+\(\frac{2}{11x14}\)+\(\frac{2}{14x17}\)< 1. Giải hẳn ra nhé
Tìm x biết :
\(\frac{1}{5\times8}+\frac{1}{8\times11}+\frac{1}{11\times14}+.....+\frac{1}{x\times\left(x+3\right)}=\frac{101}{1540}\)