\(\dfrac{1}{1x2}\)+\(\dfrac{1}{2x3}\)+\(\dfrac{1}{3x4}\)+......+\(\dfrac{1}{9x10}\)
Tính bằng cách nhanh nhất
So sánh:
A=\(\dfrac{1}{1x2}\)+\(\dfrac{1}{2x3}\)+.....+\(\dfrac{1}{49x50}\) với 1
B=\(\dfrac{1}{2x4}\)+\(\dfrac{1}{4x6}\)+.....+\(\dfrac{1}{46x48}\) với \(\dfrac{1}{4}\)
C=\(\dfrac{1}{6}\)+\(\dfrac{1}{12}\)+.....+\(\dfrac{1}{110}\)+\(\dfrac{1}{122}\) với \(\dfrac{1}{2}\)
Giải tất cả các câu đầy đủ phép tính giúp mik nha. C.ơn
B= \(\dfrac{1}{1x2}\)+\(\dfrac{1}{2x3}\)+\(\dfrac{1}{3x4}\)+.....+\(\dfrac{1}{198x199}\)+\(\dfrac{1}{199x200}\)
Tìm x biết:
\(\dfrac{x}{x+1}=\dfrac{1}{1x2}+\dfrac{1}{2x3}+\dfrac{1}{3x4}+...+\dfrac{1}{31x32}\)
Trả lời nhanh giúp mìn nhé
Tìm x:
(x -\(\dfrac{1}{3}\) ) x (\(\dfrac{2}{1x2}\)+ \(\dfrac{2}{2x3}\)+ \(\dfrac{2}{3x4}\) + … + \(\dfrac{2}{9x10}\)) = \(\dfrac{3}{4}\)
a.1x2+2x3+3x4+.........+19x20
b. 3x4+4x5+5x6+.........+49x50
A = \(\dfrac{1}{2}+\dfrac{1}{2x3}+\dfrac{1}{3x4}+............+\dfrac{1}{9x10}\)
tính nhanh
D=\(\dfrac{5}{1x2}\)+\(\dfrac{5}{2x3}\)+\(\dfrac{5}{3x4}\)+....+\(\dfrac{5}{199x200}\)
E=\(\dfrac{0,5}{1x2}\)+\(\dfrac{0,5}{2x3}\)+\(\dfrac{0,5}{3x4}\)+......+\(\dfrac{0,5}{198x199}\)+\(\dfrac{0,5}{199x200}\)