Question

log2(2x^2+4)-log2(x^2-x+10)>=log2(2-1/x)

Answer 1

$\displaystyle log_2(2x^2+4)-log_2(x^2-x+10) \geq log_2(2- \frac{1}{x})\\\\ODZ: \\\\ 2x^2+4\ \textgreater \ 0; x\in R\\\\x^2-x+10\ \textgreater \ 0; x\in R\\\\ \frac{2x-1}{x}\ \textgreater \ 0; x\in (-oo;0)(1/2;+oo)$

решение: 
$\displaystyle log_2 \frac{2x^2+4}{x^2-x+10} \geq log_2( \frac{2x-1}{x})\\\\ \frac{(2x^2+4)*x-(2x-1)(x^2-x+10}{x(x^2-x+10)} \geq 0\\\\ \frac{2x^3+4x-2x^3+3x^2-21x+10}{x(x^2-x+10)} \geq 0\\\\ \frac{3x^2-17x+10}{x(x^2-x+10)} \geq 0\\\\ \frac{(x-5)(3x-2)}{x(x^2-x+10)} \geq 0$


____-___ 0 ____+_____2/3_____-___5____+___

(0;2/3][5;+oo)

с учетом ОДЗ
ОТВЕТ (1/2; 2/3][5;+oo)