Question

S=3/1*4+3/4*7+3/7*10+3/10*13+3/13*16

 

Answer 1

 \(S=\frac{3}{1.4}+\frac{3}{4.7}+\frac{3}{7.10}+\frac{3}{10.13}+\frac{3}{13.16}\)

  \(=1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+\frac{1}{10}-\frac{1}{13}+\frac{1}{13}-\frac{1}{16}\)

  \(=1-\frac{1}{16}\)

   \(=\frac{15}{16}\)

Study well ! >_<

Answer 2

S = 3/(1*4) + 3/(4*7) + 3/(7*10) + 3/(10*13) + 3/(13*16)

S = 1 - 1/4 + 1/4 - 1/7 + 1/7 - 1/10 + 1/10 - 1/13 + 1/13 - 1/16

S = 1 - 1/16

S = 15/16

Vậy S = 15/16