Math Snap

STEP 1

1. A line without a $y$-intercept is a vertical line.
2. A vertical line is represented by an equation of the form $x = c$, where $c$ is a constant.
3. We are given four equations and need to determine which one represents a vertical line.

STEP 2

1. Identify the form of each equation.
2. Determine which equation represents a vertical line.

STEP 3

Identify the form of each equation.
- (a) $y = 4$ is a horizontal line with a $y$-intercept at $(0, 4)$.
- (b) $x = -4$ is a vertical line with no $y$-intercept.
- (c) $x + y = 2$ can be rearranged to $y = -x + 2$, which is a line with a $y$-intercept at $(0, 2)$.
- (d) $y = 3x$ is a line with a $y$-intercept at $(0, 0)$.

Determine which equation represents a vertical line.
From STEP_1, we identified that equation (b) $x = -4$ is a vertical line.
The equation that represents a line without a $y$-intercept is:
$\boxed{x = -4}$