Bonjour,
1) F = 2x(4x-1)-(4x-1)²
= 8x²-2x - (16x²-8x+1)
= 8x² - 16x² - 2x + 8x - 1
= -8x² + 6x - 1
2) F = 2x(4x-1)-(4x-1)²
= 2x(4x-1)-(4x-1)(4x-1)
= (4x-1)(2x-(4x-1))
= (4x-1)(-2x+1)
= -(4x-1)(2x-1)
3) si x = -1 alors F = -8(-1)²+6(-1)-1 = -8-6-1 = -15
