Number Lines and Solution Sets (F)

If the solution is ‘greater than’ (>) or ‘less than’ (<) then the circle stays open. If the solution includes ‘equal’, as in ≤ (less than or equal to) and ≥ (greater than or equal to) then the circle should be filled in. The direction of the arrow is important – ‘Less than’ goes Left, ‘gReater than’ goes Right.

When an inequality is bounded by an upper and a lower limit, such as -2 < x ≤ 5, this can be drawn as a line with a circle at each end – open at -2, and closed at 5.

If you use a number line to help work out a sum involving negative numbers, it doesn’t need to be drawn to scale. In fact, it doesn’t need all the numbers written in, just the key ones – the numbers from the question, plus the all-important zero. Then decide if you are moving left or right from the start point, and do you go across the zero line?