Which of the following represents a linear equation?

A linear equation is characterized by having a degree of 1, meaning that the highest exponent of the variable (in this case, x) is 1. In the context of the choices given, the correct representation of a linear equation is one that can be expressed in the form y = mx + b, where m represents the slope and b represents the y-intercept.

When examining the equation y = 3x + 5, it fits this form perfectly. The variable x is raised to the first power, and the equation depicts a straight line when graphed. The slope, which is 3, indicates how steep the line is, and the y-intercept, which is 5, tells where the line crosses the y-axis.

In contrast, the other equations do not represent linear equations due to their varying degrees. For instance, y = x² + 2 features x raised to the power of 2, making it a quadratic equation rather than linear. Similarly, y = 2/x is a rational function, and the relationship is not linear since it cannot be rewritten in the form of a straight line; it creates a hyperbolic curve instead. Lastly, y = √x represents a square root function, indicating