Question

What is the vertex of y = 2|x| – 1 ?

Answer 1

the vertex would be a (0,-1)

Answer 2

for a normal absolute value function, the vertex is at (0,0)

Answer 3

stretching the function vertically does not effect the vertex

Answer 4

however, shifting the function down by one does make the vertex one lower

Answer 5

so you get:
(0,-1)