Réponse :
bonjour
C (x) = ( x - 3 ) ( 5 - 2 x )
C ( - 2 ) = ( - 2 - 3 ) ( 5 + 4 ) = - 5 * 9 = - 45
C ( - 1 ) = ( - 1 - 3 ) ( 5 + 2 ) = - 4 * 7 = - 28
C ( 1/2 ) = ( 1/2 - 3 ) ( 5 - 2/2 ) = ( 1/2 - 6/2 ) ( 10/2 - 2/2 )
= - 5/2 * 8/2 = - 40/4 = - 10
D (x) = - 2 x² + 11 x - 15
D ( -2 ) = - 2 ( - 2)² + 11 *- 2 - 15 = - 4 - 22 - 15 = - 41 et pas - 45
D ( -1 ) = - 2 ( - 1 )² + 11 *-1 - 15 = - 2 - 11 - 15 = - 28
D ( 1/2 ) = - 2 ( 1/2)² + 11 * 1/2 - 15 = - 2 *1/4 + 11/2 - 15
= - 2/4 + 22/4 - 60/4 = - 40/4 = - 10
Explications étape par étape :
