On donne l'expression C= (12x+3)(2x-7)-5x(2x-7)

bonjour

C = 24 x² - 84 x + 6 x - 21 - 10 x² + 35 x
C = 14 x² -43 x - 21

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

pour x = 1
C = (2 -7) ( 7 +3) = - 5 x 10 = -50

C= (12x+3)(2x-7)-5x(2x-7)1)
C = 24x²-84x+6x-21-10x²+35
C = 14x²-78x+14

2)
on met 2x-7 en facteur
C = (2x-7)(12x+3-5x)
C = (2x-7)(7x+3)

3)
C = (2-7)(7+3)
C = -5x10
C = -50