These two phrases mean basically the same thing and emphasize that they are not to worry about what happened in the past. (See: [[rc://en/ta/man/translate/figs-parallelism]])
Yahweh uses a question to teach the people of Israel. This rhetorical question can be translated as a statement. AT: "surely you have noticed it." (See: [[rc://en/ta/man/translate/figs-rquestion]])