California Assessment of Student Performance and Progress (CAASPP) Math Practice Exam

Which type of function is characterized by a straight-line graph?

1. Quadratic Function

2. Cubic Function

3. Linear Function

4. Exponential Function

The correct answer is: Linear Function

A function that is characterized by a straight-line graph is a linear function. Linear functions can be represented in the form of \(y = mx + b\), where \(m\) is the slope and \(b\) is the y-intercept. The constant rate of change, represented by the slope, ensures that for every unit increase in \(x\), the value of \(y\) changes by a constant amount. This creates a straight-line graph when plotted on a coordinate plane. In contrast, quadratic functions produce a parabolic graph, which opens either upwards or downwards, depending on the coefficient of the squared term. Cubic functions contain a variable raised to the third power and typically produce an S-shaped curve, reflecting two bends. Exponential functions increase or decrease at an accelerating rate, leading to a curve that approaches zero but never touches the x-axis for positive bases. These characteristics differentiate them distinctly from the straight-line graph of a linear function.