When you are learning to recognise and sketch equations of lines, a lot of emphasis is put on finding equations of diagonal lines (so called y = mx + c lines).
The thing that is commonly skated over is recognising and drawing lines of the form x = a and y = b.
x = a and y = b
To put it simply, these are horizontal and vertical lines.
Lines with the equation x = a are vertical lines that go through the x-axis at the point a.
All the points on this line have an x coordinate of a.
Lines with the equation y = b are horizontal lines that go through the y-axis at point b.
All the points on this line have a y coordinate of b.
Let's have a go at some questions.