Как решить уравнение x^2+4/x^2=x+2/x+2. Created by hirnyiigor. matematika-ru

x+2...

sstavridka

Ответ:

$x^2+\dfrac{4}{x^2}=x+\dfrac{2}{x}+2\ \ ,\ \ \ \ ODZ:\ x\ne 0\ ,\\\\\\t=x+\dfrac{2}{x}\ \ ,\ \ t^2=x^2+4+\dfrac{4}{x^2}=\Big(x^2+\dfrac{4}{x^2}\Big)+4\ \ \to \ \ x^2+\dfrac{1}{x^2}=t^2-4\ ,\\\\\\t^2-4=t+2\ \ ,\ \ t^2-t-6=0\ \ ,\ \ t_1=-2\ \ ,\ \ t_2=3\ \ (teorema\ Vieta)\\\\a)\ \ x+\dfrac{2}{x}=-2\ \ ,\ \ \dfrac{x^2+2}{x}+2=0\ \ ,\ \ \dfrac{x^2+2x+2}{x}=0\\\\\\x^2+2x+2=0\ \ \ \ ,\ \ D/4=1-2=-1$

$b)\ \ x+\dfrac{2}{x}=3\ \ ,\ \ \dfrac{x^2+2}{x}-3=0\ \ ,\ \ \dfrac{x^2-3x+2}{x}=0\ \ ,\\\\\\x^2-3x+2=0\ ,\ \ x_1=1\ ,\ x_2=2\ \ (teorema\ Vieta)\\\\\\Otvet:\ \ x_1=1\ ,\ x_2=2\ .$