Sketch the graph of y = |x-2a|, where a is a positive constant.

Mark scheme

Marking points from the official mark scheme (May/June 2024). The mark or mark type is shown in brackets.

1. [B1] Correct shape, roughly symmetrical. Both sections should be solid straight lines. If not drawn with a ruler the intention must be clear. 2a marked on each axis (must be 2a, not just 2). Needs to extend into negative x. If a is given a value, then B0. Ignore y = 2x - 3a if seen.
2. [B1] Solve linear equation or inequality to obtain critical value x = a or exact equivalent. Ignore x = a if seen.
3. [B1] Accept x < a or (-∞,a). Must be strict inequality. Need a clear final solution: x > a or x < a must be rejected if seen as part of the working. Rejection can be implied, e.g. if only the correct inequality is underlined. B0 B0 if a is given a value.