Given that
And
Comparing both functions we see that g(x) is 3 times more than f(x) so we can write:
g(x)=3 f(x)
Now using g(x)=3 f(x), we have to tell what type of transformation occurs from f(x) to g(x).
Remember that when some number is multiplied with f(x) then that either compresses or stretches the given function.
when multiplied number is greater than 1 the it creates stretch.
in g(x)=3 f(x), we see that multiplied number 3 is more than 1 so that indicates stretch.
Hence choice D) g(x) stretches vertically by factor of 3. is correct.