The figure below shows the graph of [math] and the graph of its local linearization [math] at [math]. (The local linearization is shown in blue.)

What is the value of [math]?
[math]

What is the value of [math]?
[math]

Use the linearization to approximate the value of [math].
[math]

Is the approximation an under- or overestimate?
(Enter under or over.)