Bonjour,
1) E = (2x - 3)(x + 8) - (2x - 3)²
= 2x² + 16x - 3x - 24 - (4x² - 12x + 9)
= -2x² + 25x - 33
2) E = (2x - 3)(x + 8) - (2x - 3)²
= (2x - 3)(x + 8) - (2x - 3)(2x - 3)
= (2x - 3)[(x + 8) - (2x - 3)]
= (2x - 3)(-x + 11)
3 ) si x = -2
E = (2(-2)-3)(-(-2)+11)
= (-4-3)(2+11)
= (-7)(13)
= -91
ou E = -2(-2)²+25(-2)-33
= -8 - 50 - 33
= -91