\(\frac{1}{3\times4}+\frac{1}{4\times5}+\frac{1}{5\times6}+...+\frac{1}{11\times12}\) =\(\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+...+\frac{1}{11}-\frac{1}{12}\) =\(\frac{1}{3}-\frac{1}{12}\) =\(\frac{1}{4}\)
1/3x4 + 1/4x5 + 1/5x6 + ...........+ 1/11x12
1/3x4 + 1/4x5 + 1/5x6 + .........+ 1/11x12 =
Tính 1/3x4+1/4x5+1/5x6+1/6x7+1/7x8+1/8x9+1/9x10+1/10x11+1/11x12
1/3x4+1/4x5+1/5x6+....+1/11x12
tính nhanh
1/2x3 + 1/3x4 + 1/4x5 + 1/5x6 + 1/6x7
1/2x3 + 1/3x4 + 1/4x5 + 1/5x6 + 1/6x7 + 1/20x21
\(\frac{1}{3x4}\)+ \(\frac{1}{4x5}\) + \(\frac{1}{5x6}\) + \(\frac{1}{6x7}\)+ ............. + \(\frac{1}{11x12}\) = ?
Tính nhanh:
1+1/3x4+1/4x5+1/5x6
\(\frac{1}{3x4}\) + \(\frac{1}{4x5}\) + \(\frac{1}{5x6}\) + \(\frac{1}{6x7}\)+.........+\(\frac{1}{11x12}\)
Tính nhanh : 1/2x3 + 1/3x4 + 1/4x5 + 1/5x6 + 1/6x7
