单调性

f′>0⇒f↗f'>0 \Rightarrow f\nearrow

f′<0⇒f↙f'<0 \Rightarrow f\swarrow

f′≡0⇒f=Cf' \equiv 0 \Rightarrow f=C

凹凸性

f′′>0⇒∪ f''>0 \Rightarrow \cup //凹

f′′<0⇒∩f''<0 \Rightarrow \cap //凸

f′′≡0⇒/f'' \equiv 0 \Rightarrow / //即斜直线