Pre-image abcd is dilated to image a'b'c'd'. squares what scale factor is used to create the dilation? 3 1/3 9 1/9

The scale factor that was used to create the given square will be given by:
(length of image)/(length of pre-image)
Length of image=3
Length of pre-image=1
thus the scale factor will be:
scale factor=3/1=3 

3

The scale factor that is used to create the dilation is a scale factor of 3.  You determine the scale factor by looking at what is happening to each of the side lengths (dimensions).  The original has side lengths of 1, and the new one has side lengths of 3.  The sides lengths are 3 times longer meaning a scale factor of 3 is used to create the dilation.