Answer:
( 2m - n + p )² - ( 2m + n - p )² = 4m² + n² + p² - 4mn + 4mp - 2np - ( 4m² + n² + p² + 4mn - 4mp - 2np ) = 4m² + n² + p² - 4mn + 4mp - 2np - 4m² - n² - p² - 4mn + 4mp - 2np = -8mn + 8mp
