Answer:
Scale factor(k) defined as:

As per the statement:
The original length of AB is 9 centimeters.
A dilation with a scale factor of 2 is applied to AB.
⇒k = 2
We have to find the length of the image of AB after the dilation is applied.
Using definition of scale factor:

Substitute the given values we have;

Multiply both sides by 9 we have;

or

therefore, the length of the image of AB after the dilation is applied. is, 18