\(\frac{1}{1x4}\)+\(\frac{1}{2x6}\)+\(\frac{1}{3x8}\)+...........+\(\frac{1}{99x200}\)=?
5/12+1/3x8 -1/6
1/2x6+1/4x9+1/6x12+............+1/16x27+1/18x30
1/1x4+1/4x7+...+1/34x37+1/37x40..
(1+1/2+1/3+....+1/9+1/10)/ (1/1x10+1/2x9+1/3x8+....+1/8x3+1/9x2+1/10x1)
Tính nhanh
(1+1/2+1/3+....+1/9+1/10)/ (1/1x10+1/2x9+1/3x8+....+1/8x3+1/9x2+1/10x1)
Tính nhanh
1/6+2/3x8/9
Tìm a:
A= \(\dfrac{1}{1x4}\)+\(\dfrac{1}{1x7}\)+\(\dfrac{1}{7x10}\)+.....+\(\dfrac{1}{100x103}\)