Réponses

2014-05-11T13:07:24+02:00
a) A = 5(x+3) - 7(x-5) - 5x
A = (5*x + 5*3) + (7*x - 5*7) - 5x
A = 5x + 15 + 7x - 35 - 5x
A = 7x - 20

b) Si x = 3/7, alors :
A = 7 * 3/7 - 20
A = -17