d= 6(3x²-4x+9) e= 8x+x(-9x+4) f=7x(5x-4-2x(9-7x)

Bonsoir

d = 6(3x² - 4x + 9)
   = 18x² - 24x + 54

e = 8x + x(-9x + 4)
   = 8x - 9x² + 4x
   = -9x² + 12x

f = 7x(5x - 4) - 2x(9 - 7x)
  = 35x² - 28x - 18x + 14x²
  = 49x² - 46x

d= 6(3x²-4x+9)
=18x²-24x+54

e= 8x+x(-9x+4)
=8x-9x²+4x
=-9x²+12x

f=7x(5x-4)-2x(9-7x)
=35x²-28x-18x+14x²
=49x²-46x