this is because the graph must be concave up in order for the linear approximation to be less than the actual function
The local linear approximation of a function f will always be less than or equal to the function's value if, for all x in an interval containing the point of tangency:
a. f' > 0
b. f' < 0
c. f" > 0
d. f" < 0
e. f' = f" = 0
I have no idea what the answer is so I'd appreciate it if someone could please give me a detailed explanation.