Question

tính giá trị biểu thức : S= 1+1/2.(1+2)+1/3.(1+2+3)+...+1/100.(1+2+...+100)

Answer 1

1/1+2+1/1+2+3+1/1+2+3+4+...+1/1+2+3+...+99 +1/50 

=1/(2+1).2:2+1/(3+1).3:2+1/(4+1).4:2+..+1/(99+1).99:2+1/50

=2/2.3+2/3.4+2/4.5+..+2/99.100+1/50

=2(1/2.3+1/3.4+1/4.5+..+1/99.100)+1/50 

=2(1/2-1/3+1/3-1/4+1/4-1/5+...+1/99-1/100)+1/50 

=2(1/2-1/100)+1/50

=49/50+1/50=1 

Answer 2

Sai rồi!!!!!!!!!!!!!!!!

Answer 3

S= 1+1/2(1+2) +1/3(1+2+3)+...+1/100(1+2+...+100)

S= 1+1+1/2 + 2 + 2+1/2+...+ 50+1/2

S= 1+1,5+2+2,5+3+3,5+...+50,5

  = (50,5+1)*99:2

  = 51,5*99/2

  = 2575