bonjour
1 ) a² - b² = ( a + b ) ( a - b )
1012 ² -988 ² = ( 1012 + 988 ) ( 1012 - 988)
2. ( x - 3 )² - ( x - 1 ) ( x - 2 )
= x² - 6 x - ( x² - 2 x - x + 2 )
= x² - 6 x - x² + 3 x - 2
= - 3 x - 2
997 ² - 998 x 999
= ( 1 000 - 3 )² - ( 1000 - 2 ) ( 1 000 - 1 )
