To express a linear function in the form of a linear equation, we can use the slope-intercept form, which is given by:
\[ y = mx + b \]
where:
- \( m \) is the slope,
- \( b \) is the y-intercept (initial value).
Given that the slope \( m = 3 \) and the initial value (y-intercept) \( b = -1 \), we can substitute these values into the equation:
\[ y = 3x - 1 \]
Thus, the linear equation representing the function is:
\[ y = 3x - 1 \]