Question

This is part of Ivan's homework. A line segment, AB, goes from the point A(4, 7) to the point B(9, 3). AB is translated 3 squares left and 2 squares down. The image of AB is AB. Work out the coordinates of A' and B. Solution A' is at (7, 5). B' is at (12, 1). Ivan has worked out the coordinates of A' and B' incorrectly.

Explain the mistake that he has made.​

Answer 1

Ivan mixed up left and right.

He mistakenly added 3 to the x coordinate to shift the points 3 units right, when instead he should have subtracted 3 from the x coordinate to go 3 units left.

Luckily, Ivan correctly shifted the points 2 units down.

The coordinates of A' and B' should be (1,5) and (6,1) respectively.

Refer to the diagram below.