Answer: g(x) = 3|x|
Reason:
The output of a function is the y value. We can say that y = f(x).
Vertically stretching the graph by a factor of 3 means that the points are 3 times as tall compared to before. For example, the point (1,1) jumps to (1,3).
The x coordinate stays the same, but the y coordinate has been tripled.
Therefore, we simply tack a 3 out front the absolute value bars to go from |x| to 3|x|