Réponse :
Bonjour,
A= x*9x = 9x²
B= 7x*7x = 49x²
C= -3 + (5x+2) * (-6x+5) = -3 + 5x*(-6x) +5x*5 +2*(-6x)+2*5 = -3 -30x² +25x-12x +10 = -30x²+13x + 7
D= 4x² + (-2x-3)*(-x-9) = 4x² + (-2x)*(-x) –(2x)*(-9) -3*(-x)-3*(-9) = 4x² +(2x²) – (-18x) – (-3x) – (-27)= 4x² +2x²+18x+3x+27 = 6x²+21x+27
E= (-6x-5)*(7x-4)+8x-2 = (-6x)*7x – 6x*(-4) -5*7x -5*(-4) +8x-2 = -42x²+24x-35x+20+8x-2 = -42x²-3x+18
