Question

Which of these describes the effect changing
f
(
x
)
to
f
(
−
2
x
)
will have on the graph?


The graph will translate down 2 units.


The graph will change from opening up to opening down.


The graph will stretch horizontally.


The graph will shrink horizontally.

Answer 1

The graph will shrink horizontally.

More precisely, f(-2x) = f(bx) with b = -2 compresses the graph horizontally by factor 1/|b| = 1/2 (points move halfway to the y-axis) and the negative sign also reflects it across the y-axis.