Question

tính tổng S= 1/6+1/12+1/20+1/30+1/42+1/56

Answer 1

S= \(\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+\frac{1}{5.6}+\frac{1}{6.7}+\frac{1}{7.8}\)

S= 1/2 - 1/3 + 1/3 - 1/4 + 1/4 - 1/5 +  1/5 -1/6 +1/6 - 1/7 + 1/7 - 1/8

S= 1/2 - 1/ 8 

S= 3/8

Answer 2

S= 1/2.3 + 1/3.4 + 1/4.5 + 1/5.6 + 1/6.7 + 1/7.8

  = 1/2 - 1/3 + 1/3 - ...+ 1/7 - 1/8

  = 1/2 - 1/8

  = 3/8

Answer 3

S=(1/2.3) +(1/3.4) + (1/4.5) +...+1/7.8

S=1/2-1/3+1/3-1/4 +1/4-1/5+...+1/7-1/8

S=1/2-1/8

S=3/8

Answer 4

Nhi Nhi ơi mk nhà ai ngang qua cho xin 1