AP Calculus AB and BC glossary
Justification
A justification is the sentence of reasoning that supports an answer on free response. A correct conclusion without one routinely earns no credit, because the point is awarded for the reason, and the reason must name the specific fact you used.
Cite the actual condition. Say that the derivative changes from positive to negative at that point, or that the function is continuous on a closed interval so the theorem applies, rather than saying it is obvious from the graph.
The mistake
Describing the calculation instead of the reason. Saying you set the derivative to zero explains what you did; the point comes from saying why that gives a maximum.
Appears in: Unit 5: Analytical Applications