bonjour
( 2 x + 1 ) ( 1 - x ) + 4 x + 2
= ( 2 x + 1 ) ( 1 - x ) + 2 ( 2 x + 1 )
= ( 2 x + 1 ) ( 1 - x + 2 )
= ( 2 x + 1 ) ( - x + 3 )
( 2 x - 5 )² - 4 x + 10
= ( 2 x - 5 )² - 2 ( 2 x - 5 )
= ( 2 x - 5 ) ( 2 x - 5 - 2 )
= ( 2 x - 5 ) ( 2 x - 7 )
A (x) = x ( x + 13 ) - 5 ( x - 3 )
A (x) = x² + 13 x - 5 x + 15
A (x) = x² + 8 x + 15
A (x) = ( x + 4 )² - 1 = x² + 8 x + 16 - 1 = x² + 8 x + 15
A (x) = ( x + 4 ) ² - 1
A (x) = ( x + 4 - 1 ) ( x + 4 + 1 ) = ( x + 3 ) ( x + 5 )
voilà pour 2 , essaie de faire le 3