progrỉnam bai1;
var n,i:longint;
s:real;
begin
write('N= ');readln(n);
s:=0;
for i:=1 to n do
s:=s+1/i*(i+1);
writeln('Tong la ',s);
readln
end.
1) var n,i:integer;
s:real;
begin
write('n=');readln(n);
s:=0;
for i:=1 to n do s:=s+(1/(i*(i+1)));
writeln(' Tong la: ',s);
readln;
end.
2) var n,i:integer;
s:real;
begin
write('n=');readln(n);
s:=0;
for i:=1 to n do s:=s+(1/((2*i)-1));
writeln(' Tong la: ',);
readln;
end.