P3.4.3 - Reciprocal derivative relationship

Use dy/dx = 1/(dx/dy), including finding dy/dx when x is given as a function of y.

Use reciprocal derivative relationship to connect the rule to the data and decision in the question.

This matters because reciprocal derivative relationship determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply reciprocal derivative relationship to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: Reciprocal derivative relationship is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.