Science:Math Exam Resources/Courses/MATH110/April 2013/Question 09 (b)/Solution 1

The function $\displaystyle f(x)=e^{x}$ is concave up, so all tangent lines, including our linear approximation, will lie below the graph.

The purple graph is f(x), the blue line is the linear approximation L(x) = x+1 from part (a). Thus our linear approximation is an underestimate.