19
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Use the identity:
Applying this to (x - y)(x - y), we get:
Rearranging and substituting the given conditions into this expansion:
- x² - 2xy + y² =
- x² + y² - 2xy =
- 25 - 2*3 =
- 25 - 6 =
- 19
Therefore, the result of the expansion is 19.
