tính nhanh:1/1x2+1/2x3+1/3x4+...+1/13x14
1.3-3.2+5.1-7+8.9-10.8+...+43.1
giúp mình làm bài này với
Tính B= \(\dfrac{1}{3.4}\)-\(\dfrac{1}{4.5}\)-\(\dfrac{1}{5.6}\)-\(\dfrac{1}{6.7}\)-\(\dfrac{1}{7.8}\)-\(\dfrac{1}{8.9}\)-\(\dfrac{1}{9.10}\)
Tính hiệu giữa A và B.
A=1/2.3+2/3.4+3/4.5+...+7/8.9+8/9.10
B=1/2+1/3+1/4+1/5+1/6+...+1/9
A = 1 / 6x7 + 1/7.8 + 1/8.9 + . . . + 1/2017x2018
(1/1.2+1/2.3+1/3.4+.......+1/8.9+1/9.10) .100-(5/2:(x +206/100):1/2=89
(1/1.2 + 1/2.3+ 1/3.4+...+ 1/8.9 + 1/9.10) .100 - [5/2: (x + 206/100)] : 1/2 =89
Tính nhanh :
1.3 - 3.2 + 51.7 + 8.9 - 10.8 + 12.7 - 14.6 + 16.5
tìm x trong biểu thức sau
(1/1.2=1/2.3+1/3.4+.....+1/8.9=1/9.10).100-[5/2:(x+206/100)]:1/2=89
Tunh:
\(\frac{1}{8.9}+\frac{1}{9.10}+\frac{1}{10.11}+...+\frac{1}{210.211}+\frac{1}{211.212}\)
Help me ~~~