Réponse:
A= 12x -2x^2 (le ^2 signifie au carré)
B= 7x-9
C= 12x^2
D= 3x
Explications étape par étape:
A= 5x + x×7 + x×(-2)x
= 5x + 7x - 2x^2 ( car - × + = -)
B = 3×4x - 3×3 -5x
= 12x -9 -5x = 7x-9
C= 6x^2 - 2x×4 + (-3)x×(-2)x +8x
= 12x^2
D. (3-5x)x +5x
= 3x -5x^2 +5x^2
= 3x
