the tangent line, , serves as an approximation of function values close to x = 2.

for values of x close to x = 2.

... as far as an "over" or "under" estimate, look at the tangent line and the concavity of f(x) on both sides of x = 2.

... the tangent line and f(x) have the same value at x = 2. What do you think happens to the accuracy of the approximation as x gets farther away from x = 2?