The majority of operations select an expression enclosed between text and binary operations. Place the insertion point anywhere in the left side of the equation 2x + 3x = 1 + 4 except to the left of the 2, and choose Evaluate.
Evaluate
2x + 3x = 5x = 1 + 4
The expression = 5x is inserted immediately after the expression 2x + 3x. This time, Scientific Notebook selected only the left side of the equation for evaluation. Since the result of the evaluation was equal to the original expression, the result was placed next to the expression, preceded by an equals sign. The insertion point is placed at the right end of the result so that you can select another operation to apply to the result without moving the insertion point.
Other commands, including Evaluate Numerically, Simplify, Combine, Factor, and Expand, make similar selections under similar conditions.