Question

The coordinates of △ABC are A(−11,7), B(−5,−3), C(−2,3). After a dilation, the coordinates are A'(22,−14), B'(10,6), C'(4,−6). Find the scale factor.

Answer 1

Answer:

-2

Step-by-step explanation:

Before a dilation you have the point (x,y).

After a dilation of a scale factor of r you have (r*x,r*y).

Let's look at one pair of corresponding points.

A(-11,7)  and A'(22,-14)

We need to figure out what we can multiply to -11 to get 22.

We need to figure out what we can multiply to 7 to get -14.

Hopefully it is the same number or this isn't a dilation.

So to get from pre-image to image you need to multiply by -2 because -11*-2=22 and 7*-2=-14.

The scale factor is -2.

The dilation is this: (x,y)->(-2x,-2y)