f(x) = ax3
g(x) = bx3
f(x) will be the same as (that is, map onto) g(x) if we change the a to a b. ·So if we multiply f(x) by b/a:
(b/a)f(x) = (b/a)ax3 = bx3
b/a is a vertical dilation that stretches or compresses the graph of f(x) until it matches the graph of g(x).