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Rezolvati in multimea numerelor reale ecuata 2^x^2+4x+2=64 x 2^x.

Răspuns :

Răspuns:

Explicație pas cu pas:

[tex]2 {}^{x {}^{2} + 4x + 2 } = 64 \times 2 {}^{x} [/tex]

[tex]2 {}^{x {}^{2} + 4x + 2 } = 2 {}^{6} \times 2 {}^{x} [/tex]

[tex]2 {}^{x {}^{2} + 4x + 2 } = 2 {}^{x + 6} [/tex]

[tex]x {}^{2} + 4x + 2 = x + 6[/tex]

[tex]x {}^{2} + 4x + 2 - x - 6 = 0[/tex]

[tex]x {}^{2} + 3x - 4 = 0[/tex]

[tex]a = 1 \: , \: b = 3 \: , \: c = - 4[/tex]

[tex]\Delta = b {}^{2} - 4ac = 3 {}^{2} - 4 \times 1 \times ( - 4) \\ = 9 - ( - 16) = 9 +16 = 25 > 0 \Longrightarrow \exists \: \: x_1 \: , \: x_2 \in R \: \: ; \: \: x_1 \neq x_2[/tex]

[tex]x_1 = \frac{ - b - \sqrt{ \Delta } }{2a} = \frac{ - 3 - \sqrt{25} }{2} = \frac{ - 3 - 5}{2} = \frac{ - 8}{2} = - 4 \\ [/tex]

[tex]x_2 = \frac{ - b + \sqrt{\Delta} }{2a} = \frac{ - 3 + \sqrt{25} }{2} = \frac{ - 3 + 5}{2} = \frac{2}{2} = 1 \\ [/tex]

[tex] {S = \Big\{ - 4 \: , \: 1 \Big\}}[/tex]