Bonjour
Factoriser puis résoudre l'équation-produit-nul obtenue :
a) 2x2 -5x=0
x(2x - 5) = 0
x = 0 ou 2x - 5 = 0
x = 0 ou 2x = 5
x = 0 ou x = 5/2
b) 3(x+1)+12(x+1)=0
(x + 1)(3 + 12) = 0
15(x + 1) = 0
x + 1 = 0
x = -1
c) 36x2-16=0
(6x)^2 - 4^2 = 0
(6x - 4)(6x + 4) = 0
6x - 4 = 0 ou 6x + 4 = 0
6x = 4 ou 6x = -4
x = 4/6 ou x = -4/6
x = 2/3 ou x = -2/3
d) 100- 49x2=0
10^2 - (7x)^2 = 0
(10 - 7x)(10 + 7x) = 0
10 - 7x = 0 ou 10 + 7x = 0
10 = 7x ou 7x = -10
x = 10/7 ou x = -10/7
e) (7x+1)2-64=0
(7x + 1)^2 - 8^2 = 0
(7x + 1 - 8)(7x + 1 + 8) = 0
(7x - 7)(7x + 9) = 0
7(x - 1)(7x + 9) = 0
x - 1 = 0 ou 7x + 9 = 0
x = 1 ou 7x = -9
x = 1 ou x = -9/7
