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In the Nemeth instruction manual, you can assume that "blocked" examples are taken from the middle of a paragraph. You will notice that other examples in this section illustrate new paragraphs both in the print example and the simbraille transcription.
In example (3), if the expressions were embedded you are correct that it would not make sense to begin a new line with each expression. In this case, however, the expressions are displayed. Each displayed expression begins in the primary display cell, cell 3.