How can I apply f-modifiers to f-curves? (or can I?)

I apologize for maybe stupid question, but how can I apply modifiers to f-curves. For example if some object moves according some equation, and then I want to change a path, but only a bit, not rebuilding it form straight line.
There is no “apply” button for f-curves modifiers and I haven’t found other means to do it.

Not exactly sure what you are trying to do from what you wrote, but perhaps you want the ‘bake curve’ command.

Essentially, yes. But the problem is that blender doesn’t allow to edit baked f-curve.

I think I see what you want… OK so bake is no good for you, because you want to edit some part of the modified fcurve that does NOT have a keyframe?
Because if it did have a keyframe you could just drag the control point.
The only thing to do is to add a keyframe with the modifier in place just as if it were a regular curve. (I in the graph editor, selected channels only) but this might move your modified curve just a bit, but usually the effect is negligible…

You could also try Key>Sample keyframes, and this will give you the ‘baked modifier’ between the keyframes that you select. Trouble with this one is it does not disable the modifier, so as soon as you do this the area you select (or the whole curve if you selected it) will immediately show the effect of the modifier ‘doubled’, because you ‘applied’ it and then modified it, so you will have to delete the modifier after doing sample keyframes.
Hope that one of these options works for you.

Thanks for advice. This kinda worked, but I had to disable “modifier evaluation” every time, I wanted to insert new keyframe, because Blender also doesn’t allow to add keyframes to the curve, that is affected by modifier. For this reason “Sample keyframes” variant doesn’t work. Its sad, that I can’t just change modifier to several sample points. Or maybe this restriction (that curve, affected by modifier can’t be edited) can be disabled somewhere?