Bonjour
Développer :
(2x-5)(2x-5) + (3x+7) (2x-5)
= 4x² - 10x - 10x + 25 + 6x² - 15x + 14x - 35
= 4x² + 6x² - 10x - 10x - 15x + 14x + 25 - 35
= 10x² - 21x - 10
Factoriser :
a)(2x-5)(2x-5) + (3x+7) (2x-5)
= (2x - 5) (2x - 5 + 3x + 7)
= (2x - 5) (5x + 2)
b)5x² -7x
= x (5x - 7)
Résoudre les calculs :
a)3x-5=7
3x = 7 + 5
3x = 12
x = 12/3
x = 4
b) 5x+2=17
5x = 17 - 2
5x = 15
x = 15/5
x = 3
c) 5x +2 = x + 18
5x - x = 18 - 2
4x = 16
x = 16/4
x = 4.