Last option y = 1/2x + 9 represents a linear function because it is in the form y = mx + b, where m is the slope and b is the y-intercept. The other equations do not represent linear functions because their graphs are not straight lines.
The equation that represents a linear function is y = 1/2x + 9.
A linear function is a function whose graph is a straight line. The general form of a linear equation is y = mx + b, where m is the slope of the line and b is the y-intercept (the point where the line crosses the y-axis).
Of the four options given, only y = 1/2x + 9 is in the form of y = mx + b.
In y = 15/π, y is a constant value regardless of the value of x. So, its graph would be a horizontal line, not a straight line.
In y = x^2, the variable x is squared. So, its graph would be a curved parabola, not a straight line.
In y = 2x^3 + 2, the variable x is cubed. So, its graph would be a curved S-shaped curve, not a straight line.
Therefore, the only equation that represents a linear function is y = 1/2x + 9.