Réponse :
Explications étape par étape
A = ( 3x - 5 ) ( 8 + 2x ) + 32
⇔ A = 24x + 6x² - 40 - 10x + 32 double distributivité
⇔ A = 6x² + 14x - 8
B = ( 7 - 2x ) ( 7 + 4x ) - 6 ( 5x + 1 )
⇔ B = 49 + 28x - 14x - 8x² - 30x - 6 double distributivité et distributé simple
⇔ B = -8x²- 16x + 43
C = ( 4x + 5 ) ( 7x - 4 ) + ( 7x - 4 ) ( -5x - 4 ) 7x - 4 facteur commun
⇔ C = (7x - 4 ) [ ( 4x + 5 ) + ( - 5x + 4 ) ]
⇔ C = ( 7x - 4 ) ( 4x + 5 - 5x + 4 )
⇔ C = ( 7x - 4 ) ( -x + 9 )
3x - 2 = 5x - 7
⇔ 3x - 5x = -7 + 2
⇔ -2x = - 5
⇔ x = -5/-2
⇔ x = 5/2
5 ( 2x - 3 ) + 8 = 7 - 2x
⇔ 10 x - 15 + 8 = 7 - 2x
⇔ 10x - 7 = 7 - 2x
⇔ 10x + 2x = 7 + 7
⇔ 12x = 14
⇔ x = 14/12
⇔ x = 7/6
