Question

Решите уравнение

x^2 + 16/x^2 - 5x + 20/x = 2

Answer 1

Объяснение:

$\displaystyle\bf\\x^2+\frac{16}{x^2} -5x+\frac{20}{x}=2\\\\\\x^2+\Big(\frac{4}{x}\Big)^2 -5\Big(x-\frac{4}{x}\Big)-2=0\\\\\\\Big(x-\frac{4}{x}\Big)^2+8-5 \Big(x-\frac{4}{x}\Big)-2=0\\\\\\\Big(x-\frac{4}{x}\Big)^2-5\Big(x-\frac{4}{x}\Big)+6=0\\\\\\po\ Vieta\\\\1)x-\frac{4}{x}=3;\ x^2-3x-4=0;\ x_1=4;\ x_2=-1\\\\\\2)x-\frac{4}{x}=2;\ x^2-2x-4=0;\ D=b^2-4ac\\\\D=4+4\cdot4=20\\\\x_3=\frac{2-2\sqrt{5} }{2} =1-\sqrt{5} \\\\x_4=1+\sqrt{5} \\\\\\Otvet:4;-1;1-\sqrt{5};1+\sqrt{5}$