Réponses

2014-01-21T15:10:24+01:00
2) factoriser B(x)
B(x) = (3x+4)(5x+2)-(3x+4)(2x-5)
on met 3x+4 en facteur
B(x) = (3x+4)(5x+2-(2x-5))
B(x) = (3x+4)(5x+2-2x+5)
B(x) = (3x+4)(3x+7)

5) Résoudre B(x) = 0
B(x) = 0
or B(x) = (3x+4)(3x+7) (question 2)
donc
(3x+4)(3x+7) = 0
2 solutions
3x+4 = 0
3x = -4
x = -4/3
ou
3x+7 = 0
3x = -7
x = -7/3
B(x) admet 2 solutions : x = -4/3 et x = -7/3