1. The 'Show That' Algebraic Gap
In Edexcel Pure Maths and Cambridge 9709, when a question begins with 'Show that...', examiners already give you the target expression. If you skip a step, combine two operations into one, or fail to state the identity used, examiners will withhold the final accuracy mark.
2. The Radian Mode Catastrophe in Calculus
Calculus operations involving trigonometric functions are mathematically valid ONLY when x is measured in radians. Every year, thousands of students lose 4 to 6 marks on integration questions simply because their calculator remained in Degree mode.
3. Premature Rounding
Always carry at least 5 significant figures (or use calculator answer memory registers: Ans, A, B, C) until the final line.
4. Omitting the Constant of Integration (+ C)
When solving differential equations or performing indefinite integrals, omitting '+ C' on the initial integration step results in the immediate loss of both method and accuracy marks.
5. Sign Errors with Double Brackets
Protect negative terms with double brackets every single time: write -( (3x)² ) explicitly before simplifying.