91�ȱ�

• \(\text{x = a}\)
• \(\text{y = b}\)
• \(\text{y = cx + d}\)

For example, \(\text{x = 3}\), \(\text{y = -7}\), \(\text{y = 5x + 11}\)

Lines in the form \(\text{x = a}\) will always be vertical lines.

This is the line \(\text{x = 3}\):

Similarly, lines in the form \(\text{y = b}\) will always be horizontal lines.

For lines in the form \(\text{y = cx + d}\), you will normally be asked to complete a table of values before you draw the graph.

Let’s look at the line \(\text{y = x + 3}\).

When \(\text{x = -2}\):

\(\text{y = -2 + 3 = 1}\)

When \(\text{x = 1}\):

\(\text{y = 1 + 3 = 4}\)

When \(\text{x = 2}\):

\(\text{y = 2 + 3 = 5}\)

So the first point will have coordinates \(\text{(-2,~1)}\), the second will have coordinates \(\text{(-1,~2)}\) etc.