niveau 3em aidez moi svvvvp

1) G = ( x-5 )² - ( x-5 )( 7-2x )
= x² - 10x + 25 - 7x + 2x² + 35 - 10x
G = 3x² - 27x + 60

2) G = ( x-5 )² - ( x-5 )( 7-2x )
= ( x-5 )( x-5-7+2x )
G = ( x-5 )( 3x-12 )

3) ( x-5 )( 3x-12 ) = 0
Donc x-5 = 0
x = 5
Ou 3x - 12 = 0
3x = 12
x = 12/3
x = 4