Bonsoir
E = (3x + 2)² - (5 - 2x)(3x + 2)
1) E = (3x + 2)² - (5 - 2x)(3x + 2)
= [(3x)² + 2*3x*2 + 2²] - (5*3x + 5*2 - 2x*3x - 2x*2)
= (9x² + 12x + 4) - (15x + 10 - 6x² - 4x)
= 9x² + 12x + 4 - 15x - 10 + 6x² + 4x
= 15x² + x - 6
2) E = (3x + 2)² - (5 - 2x)(3x + 2)
= (3x + 2) [(3x + 2) - (5 - 2x)]
= (3x + 2) (3x + 2 - 5 + 2x)
= (3x + 2) (5x - 3)
3) x = -2
E = (3x + 2)² - (5 - 2x)(3x + 2)
= (3x + 2) (5x - 3)
= [(3*(-2) + 2] [(5*(-2) - 3]
= (-6 + 2) (-10 - 3)
= -4 * (-13)
= 52
Voilà j'espère avoir pu t'aider ^^