Răspuns:
1. [tex]x^{2}[/tex]-9=(x-3)(x+3)
2. [tex]x^{2}[/tex]+6x=0
x(x+6)=0 => [tex]x_{1}[/tex]=0
x+6=0, [tex]x_{2}[/tex]=-6
3. [tex]x^{2}[/tex]-0,04=0 =>
4. [tex]x^{2}[/tex]-2x+1=0
a=1, b=-2, c=1, Δ=4-4=0
[tex]x_{1,2}[/tex] = [tex]\frac{-b}{2a}=\frac{2}{2}=1[/tex]
5. [tex]x^{2}[/tex]-1=0 =>
6. [tex]x^{2}[/tex]-3x+2=0
a=1, b= -3, c=2, Δ=9-8=1
[tex]x_{1}[/tex]=[tex]\frac{3+1}{2} = \frac{4}{2} = 2[/tex]
[tex]x_{2} = \frac{3-1}{2} = \frac{2}{2} = 1[/tex]
7. [tex]x^{2}[/tex]=0 => x=0
8. 5[tex]x^{2}[/tex]+7x=0
x(5x+7)=0 => [tex]x_{1}[/tex]=0
5x+7=0, 5x=-7 => [tex]x= -\frac{7}{5}[/tex]
9. [tex]-x^{2}[/tex]=-2 | *(-1) => [tex]x^{2}[/tex]=2 => x=[tex]\sqrt{2}[/tex]
10. [tex]x^{2}[/tex]+6x+9=0
a=1, b=6, c=9, Δ=36-36=0
[tex]x_{1,2}[/tex] = [tex]\frac{-6}{2}[/tex]= -3
11. [tex]x^{2}[/tex]=-8 | *(-1)
-[tex]x^{2}[/tex]=8 => -x=2[tex]\sqrt{2}[/tex] | *(-1) => x=[tex]-2\sqrt{2}[/tex]
