Where a line crosses the axes.

Step 1 of 4

Crossing the y-axis

In $y = mx + n$⁠, the number $n$⁠ is the height at which the line crosses the $y$⁠-axis. Why? On the $y$⁠-axis $x = 0$⁠ always, and then $y = m \cdot 0 + n = n$$y =$$m \cdot 0 + n =$$n$⁠. So the point is $(0, n)$⁠.

The board shows $y = 3x - 2$⁠.

Step 2 of 4

Moving n

$m$⁠ and $n$⁠ do two different things: $m$⁠ sets how steep the line is, and $n$⁠ sets the height at which it crosses the $y$⁠-axis. Predict what happens when Intercept n changes while the slope stays the same.

Step 3 of 4

Crossing the x-axis

On the $x$⁠-axis $y = 0$⁠ always. So you find where the line crosses the $x$⁠-axis by solving the equation $mx + n = 0$⁠, as in the last Unit. The board shows $y = 2x - 6$⁠. Answer, then choose Where it crosses under Look inside.

Step 4 of 4

Both crossing points

Two points fix exactly one line. If you know where a line crosses both axes, you get $n$⁠ at once, and $m$⁠ from the rise and run between the two points.