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3. Rezolvați ecuația (x + 3)2 + (x + 5)(x – 5) = 4(x – 3).


Răspuns :

Răspuns:

Explicație:

[tex]\bf (x + 3)^2 + (x+5)\cdot(x-5) = 4(x-3)[/tex]

[tex]\bf (x + 3)^2 + (x^2-5^2)= 4(x-3)[/tex]

[tex]\bf x^2+6x+3^2 + x^2-25= 4(x-3)[/tex]

[tex]\bf 2x^2+6x+9 -25= 4(x-3)[/tex]

[tex]\bf 2x^2+6x-16= 4(x-3)~~~~\bigg|:2[/tex]

[tex]\bf x^2+3x-8= 2(x-3)[/tex]

[tex]\bf x^2+3x-8= 2x-6[/tex]

[tex]\bf x^2+3x-8- 2x+6=0[/tex]

[tex]\bf x^2+x-2=0[/tex]

[tex]\bf x^2+2x-x-2=0[/tex]

[tex]\bf x\cdot(x+2)-(x+2)=0[/tex]

[tex]\bf (x+2)\cdot(x-1)=0\implies[/tex]

[tex]\bf x+2=0\implies \red{\underline{x_{1}=-2}}[/tex]

[tex]\bf x-1=0\implies \red{\underline{x_{2}=1}}[/tex]

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