Question

x la a 3a + 1/x la a 3 a = ? Daca x la a 2a + 1/x la a 2 a = 6 iar x + 1/x = 2
Urgenttttt
Dau funda
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Answer 1

$x+ \frac{1}{x}=2$

Ridicam ambii membri ai egalitatii la cub

$(x+ \frac{1}{x} )^3=2^3$

$x^3+3x^2* \frac{1}{x}+3x* \frac{1}{x^2}+ \frac{1}{x^3}=8$

$x^3+ \frac{3x^2}{x}+ \frac{3x}{x^2}+ \frac{1}{x^3}=8$

$x^3+3x+ \frac{3}{x}+ \frac{1}{x^3}=8$

$x^3+3(x+ \frac{1}{x})+ \frac{1}{x^3}=8$

$x^3+3*2+ \frac{1}{x^3}=8$

$x^3+ \frac{1}{x^3}=8-6$

$x^3+ \frac{1}{x^3}=2$