Bonjour,
1)
5
5-7 = -2
(-2)² = 4
2)
-2
-2+5 = 3
3² = 9
3)
a)
x
x+5
(x+5)² )
(x+5)( x+5) = 0
=> x= -5
-5+5 = 0
b)
5
5-7 = -2
(-2)² = 4
On remonte :
(-3)² =9
-3 + 7 = 4
=> 4 -7 =-3
(-3)² =9
Il faut choisir 4
4)
(x +5)² = (x -7)²
x² +10x +25 = x² -14x +49
x² -x² +10x + 14x = 49 -25
24x = 24
x= 24/24 =1
Il faut choisir 1