Question

What will be the coordinates of vertex A' of the image?

(-8,-4)
(-2,-1)
(0, 0)
(1, 0)

Answer 1

I don't have the image or the transformation rule, so I can't pick the correct choice yet. Could you tell me one of these (or upload the image)?

- the original coordinates of vertex A (pre-image), or
- the transformation (e.g. "translate by (3,-2)", "dilate by 4 about the origin", "rotate 90° counterclockwise about the origin", "reflect across the y-axis", etc.), or
- the mapping of any one point (e.g. (x,y) → (x',y')) so I can infer the rule.

If it helps, here are the quick rules to compute A' from A = (x,y):

- Translation by (h,k): A' = (x + h, y + k)
- Dilation about the origin by factor k: A' = (kx, ky)
- Reflection across the x-axis: A' = (x, −y)
- Reflection across the y-axis: A' = (−x, y)
- Reflection across y = x: A' = (y, x)
- Rotation 90° CCW about origin: A' = (−y, x)
- Rotation 180° about origin: A' = (−x, −y)
- Rotation 270° CCW: A' = (y, −x)

Example: if one point (−2,−1) maps to (−8,−4), that is a dilation by 4 about the origin (because (−2)*4 = −8 and (−1)*4 = −4). Then any A = (x,y) would map to A' = (4x, 4y).

Send the missing info and I’ll pick which of the four choices is A'.