Question

The line given by -18x+7y=21 is dilated by a scale factor centered at the origin. The image of the line after dilation is given by y= 18/7x+6. What is the scale factor of the dilation?

Answer 1

3 units in the vertical direction

Explanation:

-18x + 7y = 21 → 7y = 18x + 21 → y = 18/7x + 3

6-3=3

Answer 2

2

Explanation:

`-18x+7y=21\\\\\implies y=(18)/(7)x+3`

when x = 0, y = 3

`y=(18)/(7)x+6`

when x = 0, y = 6

Therefore, the scale factor is 2 since the y coordinate has double: 3 x 2 = 6