Is the answer 50
guillermo is a professional deep water free diver.
his altitude (in meters relative to sea level), x seconds after diving, is modeled by
g(x)= 1/20x(x - 100)
how many seconds after diving will guillermo reach his lowest altitude?

Guillermo reach his lowest altitude 50 sec after diving and the lowest altitude is -125 m

Step-by-step explanation:

Let

x -----> the time in seconds

y ----> altitude in meters

we have

This is a vertical parabola open upward

The vertex is a minimum

To find out the lowest altitude, find the vertex

Complete the square

Factor the leading coefficient

Rewrite as perfect square

The vertex is the point (50,-125)

therefore

Guillermo reach his lowest altitude 50 sec after diving and the lowest altitude is -125 m (below the sea level)