Graph the function $f(x) = x + 4 / x$

Graph the secant line that passes through the points (1,5) and (8,8.5) on the same set of axes

Find the number c that satisfies the conclusion of the Mean Value Theorem for f on [1,8]

$c =$

Notice that if you graph the tangent line to the point (c,f(c)) it is parallel to the secant line.