Categorize each line as Increasing, Decreasing, or Constant.

$$\text{Change in } y = y(1) - y(0) = -2 - (-4) = -2 + 4 = 2$$

The change in $y$ for a 1-unit increase in $x$ is $\boxed{2}$.

Task 4.3: Connecting Equation to Slope

Observation: The "change in y" calculated in Task 4.2 is 2. The coefficient of $x$ in the equation $y = 2x - 4$ is also 2. This shows that the change in y for every 1-unit increase in x is equal to the coefficient of x (the gradient).

Task 5.1: The General Rule

Based on the investigation, for a linear equation in the form $y = mx + c$:

• The value of $m$ represents the gradient (slope) of the line. It indicates the rate of change of $y$ with respect to $x$.
• If $m > 0$, the line is increasing.
• If $m < 0$, the line is decreasing.
• If $m = 0$, the line is constant (horizontal).
• The value of $c$ represents the y-intercept, which is the value of $y$ when $x = 0$.