Réponse:
a. 4 - 2x(3x + 5)
a = 4 - 2x X 3x - 2x X 5
a = 4 - 6x²- 10x
a = - 6x²-10x+4
b.(-4 × 3x )(x X 9)
b = (-12x)(9x)
b = -108x²
c.(3x + 9 )²
c = (3x)² + 2(3x)(9) + 9²
c = 9x² + 54x + 81
d.(7x - 8)(4x - 6) + 10
d = 7x X 4x + 7x X (-6) + (-8) X 4x + (-8) X (-6) + 10
d = 28x²- 42x - 32x -48 + 10
d = 28x²- 74x-4
Explications étape par étape:
c* (a + b )² = a²+2ab+b²
