WeBWorK Standalone Renderer

The figure below shows the graph of $f$ and the graph of its local linearization $l_a(x) = 4 x - 1$ at $a$ . (The local linearization is shown in blue.)

a graph of a concave up function, in black, with a line, in blue, tangent to the curve when x=2

What is the value of $a$ ?
$a =$

What is the value of $f(a)$ ?
$f(a) =$

Use the linearization to approximate the value of $f(2.5)$ .
$f(2.5) \approx l_a(2.5) =$

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

You can earn partial credit on this problem.