 "Elementary proof"

Suppose for convenience that formula_67 on formula_34, and let formula_69.Let formula_70,
and choose formula_71 so that formula_72 for all
formula_73.Since formula_74, for every
formula_75 we have

hence

Now for every formula_75 we have 
On the other hand, since formula_80 is fixed it is clear that formula_81, and
so formula_82 if formula_75 is small enough.