Answer:
see below for the stretched graph; see the second attachment for the functions
Explanation:
The transformation ...
g(x) = f(x/a)
represents a horizontal stretch of f(x) by a factor of "a". You want a stretch by a factor of 4, so you can use a=4:
g(x) = f(x/4)
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Horizontal stretch by a factor of 4 means all the points on the graph of g(x) are 4 times as far from they y-axis as they are on the graph of f(x). That is, x must be 4 times as large to give the same y-value.
The graphs of f(x) and g(x) are shown in the second attachment, along with their equations.