цикл...и по ходу бесконечный...

[maladoy]

program Project1;

{$APPTYPE CONSOLE}

uses
SysUtils,math;
var n,i:integer;
x,y,fak,st:real;
begin
try
writeln ('vvedite n');
readln(n);
writeln ('vvedite x');
readln(x);
y:=0;
fak:=1;
for i := 0 to n do begin
if i = 0 then fak:=1
else fak:=fak*i;
st:=i*2;
y:=y+(power(-1,i)*power(x,st))/fak;
end;
writeln('x=',x:4:2,' n=',n,' y=',y:4:2);
readln;

except
on E:Exception do
Writeln(E.Classname, ': ', E.Message);
end;
end.