Question

The local linear approximation of a function f will always be greater than or equal to the function's value if, for all x in an interval containing the point of tangency,

f '(x) < 0

f '(x) > 0

f "(x) < 0

f "(x) > 0

Answer 1

@SolomonZelman

Answer 2

When the function is concave down the approximation will be greater.