Which of these ordered pairs could not be a dilation of (8, -4)?

(2, -1)
(2, -2)
(16, -8)
(4, -2)
What scale factor is shown in the graph?
in the comments---
An image has point W'(7, -3), and the pre-image has point W(21, -9). This is an enlargement.

True
False

Question

Which of these ordered pairs could not be a dilation of (8, -4)?

(2, -1)
(2, -2)
(16, -8)
(4, -2)
What scale factor is shown in the graph?
in the comments---
An image has point W'(7, -3), and the pre-image has point W(21, -9). This is an enlargement.

True
False

anonymous · Answer

attachment

anonymous · Answer

@Owlcoffee 
@Chumpian

freckles · Answer

so I guess the example didn't click?

freckles · Answer

$$(2,-1)=(8a,-4a) \text{ holds if } (2,-1) \text{ is a dilation of }  (8,-4) \ \text{ this means we should find the same } a \text{ such that } 2=8a \text{ and } -1=-4a $$
and if we don't than it is not a dilation

freckles · Answer

but if we do then it is

freckles · Answer

solving both of those give a=1/4
since both give the same a value 
then (2,-1) is a dilation of (8,-4)

freckles · Answer

$$(2,-2)=(8a,-4a)$$
see if you get the same a here for both equations
2=8a and -2=-4a

anonymous · Answer

okay

freckles · Answer

a way to look at the next question...
|dw:1436979028825:dw|
|dw:1436979032167:dw|
which is the longer line
the image or the image after the dilation?