Réponse :
Explications étape par étape
Bonjour
-(9x+7)(-3x-3)+81x^2-49=0
On remarque que :
81x^2 - 49 est une identité remarquable
= (9x)^2 - 7^2
= (9x - 7)(9x + 7)
(9x + 7)[-(-3x - 3) + 9x - 7] = 0
(9x + 7)(3x + 3 + 9x - 7) = 0
(9x + 7)(12x - 4) = 0
(9x + 7) * 4(3x - 1) = 0
4(9x + 7)(3x - 1) = 0
2 solutions :
9x + 7 = 0 ou 3x - 1 = 0
9x = -7 ou 3x = 1
x = -7/9 ou x = 1/3
S = {-7/9 ; 1/3}
(10x-1)(4x-9)+(4x-9)^2=0
(4x - 9)(10x - 1 + 4x - 9) = 0
(4x - 9)(14x - 10) = 0
(4x - 9) * 2(7x - 5) = 0
2(4x - 9)(7x - 5) = 0
2 solutions :
4x - 9 = 0 ou 7x - 5 = 0
4x = 9 ou 7x = 5
x = 9/4 ou x = 5/7
S = {5/7 ; 9/4}
