Код:
var h,dx,x,result:real;
function visl(h,dx,x:real):real;
begin
visl:=h/3*(sqr(dx)*sqr(cos(x+3*dx/sqr(h))))-dx*sqr(cos(x+dx/h))-sqr(dx)*sqr(cos(x+2*dx/sqr(h)));
end;
begin
x:=2.5094;
dx:=x/19;
h:=x/8;
result:=visl(h,dx,x);
writeln(result:2:10);
readln;
end.
Вроде так.