Factoriser a) w(x) = x² - 4+(x-1) (x+2) b) H (x) = x² +4x +(x+1) (x+4)
Mathématiques
yaya974
Question
Factoriser
a) w(x) = x² - 4+(x-1) (x+2)
b) H (x) = x² +4x +(x+1) (x+4)
a) w(x) = x² - 4+(x-1) (x+2)
b) H (x) = x² +4x +(x+1) (x+4)
1 Réponse
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1. Réponse Cabé
a) w(x) = x² - 4+(x-1) (x+2)
w(x) = x² - 4+(x-1) (x+2)
x²-4 est de la forme a² - b² = (a + b)(a - b)
x²-4 = (x-2)(x+2)
w(x) = (x-2)(x+2)+(x-1)(x+2)
Mettons (x+2) en facteur commun
w(x) = (x+2) (x-2+x-1)
w(x) = (x+2)(2x-3)
b) H (x) = x² +4x +(x+1) (x+4)
H (x) = x² +4x +(x+1) (x+4)
x²+4x = x(x-4)
H (x) = x(x+4) +(x+1) (x+4)
Mettons (x+4) en facteur commun
H (x) = (x+4)(x +x+1)
H (x) = (x+4)(2x+1)