Square [tex]$ABCD$[/tex] was translated using the rule [tex]\((x, y) \rightarrow (x-4, y+15)\)[/tex] to form [tex]\(A'B'C'D'\)[/tex]. What are the coordinates of point [tex]\(D\)[/tex] in the pre-image if the coordinates of point [tex]\(D'\)[/tex] in the image are [tex]\((9, -8)\)[/tex]?

A. [tex]\((13, -23)\)[/tex]
B. [tex]\((5, 7)\)[/tex]
C. [tex]\((18, 1)\)[/tex]
D. [tex]\((-6, -4)\)[/tex]



Answer :

To find the coordinates of point [tex]\( D \)[/tex] in the pre-image, given the translation rule and the coordinates of point [tex]\( D' \)[/tex] in the image, we need to reverse the translation operation.

The translation rule provided is:
[tex]\[ (x, y) \rightarrow (x-4, y+15) \][/tex]

This means that for any point [tex]\((x, y)\)[/tex] in the original pre-image, its coordinates in the image will be:
[tex]\[ (x-4, y+15) \][/tex]

Given the coordinates of point [tex]\(D'\)[/tex] in the image are [tex]\((9, -8)\)[/tex], we can set up equations to find the original coordinates of point [tex]\(D\)[/tex].

Let's denote the coordinates of point [tex]\(D\)[/tex] in the pre-image as [tex]\((D_x, D_y)\)[/tex].

According to the translation rule:
[tex]\[ (D_x - 4, D_y + 15) = (9, -8) \][/tex]

We can break this into two separate equations:
1. [tex]\(D_x - 4 = 9\)[/tex]
2. [tex]\(D_y + 15 = -8\)[/tex]

Now, let's solve these equations step by step.

Step 1: Solve for [tex]\(D_x\)[/tex]:
[tex]\[ D_x - 4 = 9 \][/tex]
To isolate [tex]\(D_x\)[/tex], add 4 to both sides of the equation:
[tex]\[ D_x = 9 + 4 \][/tex]
[tex]\[ D_x = 13 \][/tex]

Step 2: Solve for [tex]\(D_y\)[/tex]:
[tex]\[ D_y + 15 = -8 \][/tex]
To isolate [tex]\(D_y\)[/tex], subtract 15 from both sides of the equation:
[tex]\[ D_y = -8 - 15 \][/tex]
[tex]\[ D_y = -23 \][/tex]

Therefore, the coordinates of point [tex]\(D\)[/tex] in the pre-image are:
[tex]\[ (D_x, D_y) = (13, -23) \][/tex]

Hence, the correct answer is [tex]\((13, -23)\)[/tex].