Type the correct answer in the box. Use numerals instead of words.
The graphs of functions f and g are shown.

Graph shows 2 functions. First curve f begins close to Y-axis in quadrant 3 and rises through (1, 0), (4, 2), (8, 3) in quadrant 1. Second curve g begins close to Y-axis in quadrant 3 and rises through (1, 0), (4, 4), and (8, 6) in quadrant 1.

Function g is defined as . What is the value of k?

The value of k is
.