Bonjour,
21.
(x+3)+(x-4)=0
x+3+x-4=0
2x-1=0
2x=1
x=1/2
2x²-5x=0
x x (2x-5)=0
x=0
2x-5=0
x=0
x=5/2
x₁=0 , x₂=5/2
(x+1)x(x-5)=0
x+1=0
x-=0
x=-1
x=5
x₁=-1 , x₂=5
4x²-5=2x x (3+2x)
4x²-5=6x+4x²
-5=6x
6x=-1
x=-5/6
(x+1)(x+2)=2
x²+2x+x+2=2
x²+2x+x=0
x²+3x=0
x(x+3)=0
x=0
x+3=0
x=0
x=_3
x₁=-3,x₂=0
(3x-5)²=0
3x-5=0
3x=5
x=5/3
24.
x²+6x+9=0
(x+3)²=0
x+3=0
x=-3
1+8x+16x²=0
(1+4x)²=0
1+4x=0
4x=-1
x=-1/4
x²-2x+1=0
(x-1)²=0
x-1=0
x=1
x²-16=0
x²=16
x=4
x=-4
x₁=-1,x₂=4
Je te laisse faire les deux derniers. :)
25.
a.(3x+1)-(4x-2)=0
3x+1-4x+2=0
-x+3=0
-x=-3
x=3
b. Incomplet.
c.(4x+3)x(2-3x)=6
8x-12x²+6-9x=6
8x-12x²-9x=0
-x-12x²=0
-x(1+12x)=0
-x=0
1+12x=0
x=0
x=-1/12
x₁=-1/12,x₂=0
d.Incomplet
