Răspunsuri

2014-06-12T14:25:18+03:00
Stim a^{2} + \frac{1}{a^{2}} = 7 si s = a + \frac{1}{a}

Atunci,
s^{2} = (a+\frac{1}{a})^{2}
s^{2} = a^{2} + (\frac{1}{a})^{2} + 2a\frac{1}{a}
s^{2} = a^{2} + \frac{1}{a^{2}} + 2
s^{2} - 2 = a^{2} + \frac{1}{a^{2}}
s^{2} - 2 = 7
s^{2} = 9
s_1 = -3 si s_2 = + 3

Deci, S = { -3; 3 }

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