Bonsoir
E = (x - 3) + (x - 3)(1 - 2x)
1) Si x = 1, alors E = (1 - 3) + (1 - 3)(1 - 2*1)
= -2 + (-2)(1 - 2)
= -2 + (-2)(-1)
= -2 + 2
= 0
2) E = (x - 3) + (x - 3)(1 - 2x)
= x - 3 + (x - 2x² - 3 + 6x)
= x - 3 + x - 2x² - 3 + 6x
= -2x² + 8x - 6
3) Factoriser :
E = (x - 3) + (x - 3)(1 - 2x)
= 1*(x - 3) + (x - 3)(1 - 2x)
= (x - 3)[1 + (1 - 2x)]
= (x - 3)(1 + 1 - 2x)
= (x - 3)(- 2x + 2)
= 2(x - 3)(-x + 1)