## nerdyotter one year ago When the point (–5, 7) is dilated with the center of dilation at the origin, the image of the point is (–18.5, 25.9). What is the scale factor of this dilation?

1. nerdyotter

Answers: a.) 18.9 b.) 13.5 c.) 7.3 d.) 3.7

2. LynFran

|dw:1439521544235:dw|

3. LynFran

so k must =?

4. LynFran

3.7

5. LynFran

another way to do this is..

6. anonymous

The point (-5,7) has a distance from the origin of $\sqrt{74}$ (using distance formula or pythagorean theorem) and the point (-18.5, 25.9) has distance from the origin of $\sqrt{1013.06}\approx31.8286$ (againg, with distance formula or pythagorean theorem), then we divide both distances getting $\frac{ \sqrt{1013.06} }{ \sqrt{74} }=3.7$ Alternative D

7. nerdyotter

Thank you all!

8. LynFran

$-5k+0=-18.5$$-5k=-18.5$$k=-18.5/-5$$k=3.7$ ...$0+7k=25.9$$7k=25.9$$k=25.9/7$$k=3.7$