Explain, in one concise sentence, how the sign of at a point on a curve determines…

MATHEMATICS · Subjective · A Level · Mathematics · Differentiation · Differentiation

Problem

Explain, in one concise sentence, how the sign of

\dfrac{d^{2}y}{dx^{2}}

at a point on a curve determines whether the curve is concave upward or concave downward at that point.