Let's first consider the possible transformation(s) that might be applied to the parent function f(x)=bx.
Vertical Stretch or Shrink of f(x)=bx | |
---|---|
Vertical stretch, a>1y=af(x) | Vertical shrink, 0<a<1y=af(x) |
Notice that in our case b=9, so we're looking for transformation(s) of the function f(x)=9x. Now, let's consider the given function. y=21(9)x Looking at the function, we can see that the transformation is a vertical shrink by a factor of 2.