When a square with area 9 is dilated by a scale factor of k we obtain a square with area 25 Find the sum of all possible values of k

The side lengths of the original square and the new square are 3 and 5. Therefore, there are two values of k: 5/3 and -5/3. Note: you can dilate by a negative scale factor, think about the square on a cartesian plane. Therefore sum of the values of k are 0.