bonjour,
x²+6x+9= (x+3)²
(x+3)²=0
x+3=0
x=-3
1+8x+16x²= (1+4x)²
(1+4x)²=0
1+4x=0
4x=-1
x=-1/4=-0.25
x²-2x+1=(x-1)²
(x-1)²=0
x-1=0
x=1
x²-16=(x+4)(x-4)
(x+4)(x-4)=0
x+4=0 x=-4
x-4=0 x=4
25x²-9=(5x+3)(5x-3)
(5x+3)(5x-3)=0
5x+3=0 5x=-3 x=-3/5 x=-0.6
5x-3=0 5x=3 x=3/5 x=0.6
9x²-100=(3x+10)(3x-10)
(3x+10)(3x-10)=0
3x+10=0 3x=-10 x= -10/3
3x-10=0 3x=10 x= 10/3
