Question

 

S=3/1.4 +3/4.7 +3/7.10 +...+3/40.43 +3/43.46 

Answer 1

S=1-1/4+1/4-1/7+1/7-1/10+...+1/40-1/43+1/43-1/46

S=1-1/46 S=45/46<1 

vậy S <1 

  !!!

Answer 2

S=1-1/4+1/4-1/7+......+1/43 - 1/46 

  = 1-1/46

  = 45/46

Answer 3

S=1-1/4+1/4-1/7+......+1/43 - 1/46 

  = 1-1/46

  = 45/46