Bonsoir , pouvez vous me developper et reduire , factoriser les 5 expressions svp :
1) 25×^2-16-(-2×-3)(5×+4)
2) -(×-2)(-10×+7)-(-×+9)(-10×+7)
3)-(-8×-4)-(9×-7)(-8×-4)
4)-(2×+5)(4×-3)-(2×+5)(×+7)
5)(-2×+8)(×-2)+64-32×+4×^2



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Réponses

2014-01-03T19:08:46+01:00
1) 25×^2-16-(-2×-3)(5×+4) = (5x-4)(5x+4) + (2x+3)(5x+4) = (5x+4)(5x-4 + 2x +3) = 
= (5x+4)(7x-1)
2) -(×-2)(-10×+7)-(-×+9)(-10×+7) = (-10x +7)(-x+2 + x-9) = -7(-10x+7)
3)-(-8×-4)-(9×-7)(-8×-4) = (8x+4) + (9x-7)(8x+4) = (8x+4)((1 + 9x -7) = 4(2x+1)(9x-6)
4)-(2×+5)(4×-3)-(2×+5)(×+7) = -(2x+5)(4x-3+x+7) = -(2x+5)(5x+4)
5) (-2×+8)(×-2)+64-32×+4×^2
64-32×+4×^2 = (2x-8)² 
donc on a  -(2×-8)(×-2) + (2x-8)² = (2x-8)(-x+2+2x-8) = (2x-8)(x-6)