bonjour
2 x - 4 = 5 x + 2
2 x - 5 x = 2 + 4
- 3 x = 6
x = - 2
( x- 3 ) /4 = ( x - 4 ) / 3
3 x - 9 = 4 x - 16
3 x - 4 x = - 16 + 9
- x = - 7
x = 7
( x - 2 )² = 3
x² - 4 x + 4 = 3
x² - 4 x + 4 - 3 = 0
x² - 4 x + 1 = 0
( x - 1 )² = 0
x = 1
A ( x) = 9 x² - 12 x + 4 - ( 6 x² + 15 x - 4 x - 10 )
= 9 x² - 12 x - 4 - 6 x² - 15 x + 4 x + 10
= 3 x² - 23 x + 6
A (x) = ( 3 x - 2 ) ( 3 x - 2 - 2 x - 5 )
= ( 3 x - 2 ) ( x - 7 )
A (x) = 0 pour x = 2/3 ou 7
A ( - 2/3 ) = ( 3 * - 2/3 - 2 ) ( - 2 /3 - 7)
= ( - 6 /3 - 2 ) ( - 2/3 - 21/3 )
= ( - 2 - 2 ) ( - 23 /3)
= - 4 * - 23/3
= 92/3
