Answer: The required scale factor that is used for the dilation is 3.
Step-by-step explanation: Given that the rectangle ABCD is transformed to A'B'C'D' by a dilation.
We are to find the scale factor that is used for the dilation.
We know that
the scale factor of dilation is defined as

From the graph, we see that
in rectangle ABCD, the length the side AB is 2 units
and
the length of the corresponding side A'B' in the dilated rectangle A'B'C'D' is 6 units.
Therefore, the scale factor of dilation is given by

Thus, the required scale factor that is used for the dilation is 3.