Final answer:
Without specific expressions, there is not enough information to determine whether each pair of expressions forms an equation when joined with an equals sign. Equations require expressions that represent the same quantity or describe a relationship where one can be a function of the other.
Step-by-step explanation:
The question asks whether each pair of expressions forms an equation when joined with an equals sign. To form an equation, both sides when connected by an equals sign must represent the same quantity in different forms or describe a relationship between variables where one side can be considered a function of the other. Without specific expressions provided, there is not enough information to determine whether they form a valid equation or not. For instance, y = mx + b is a general form of a linear equation. If both sides of an expression fit the criteria where one side can be transformed into the other by algebraic manipulation, then they can form an equation. However, without knowing the exact expressions, we cannot make a clear determination.
For questions related to linear equations and algebraic properties, it's crucial to consider the structure and relationship between the expressions. Consider the examples from Practice Test 4 Solutions 12.1 Linear Equations, where equations such as y = 3,000(x) + 500 clearly define a relationship between x and y. In contrast, expressions like s² alone cannot form an equation without an additional expression defining the relationship to s². Therefore, based on the given information, the correct answer is D. Not enough information given to determine the answer.