Question

Решите неравенство: х2>2х+15

Answer 1

$x^2 textgreater 2x+15\ x^2-2x textgreater 15\ x^2-2x+1-1 textgreater 15\ (x-1)^2 textgreater 16\ |x-1| textgreater 4\ left[begin{array}{ccc}x-1 textgreater 4\ x-1 textless -4end{array}rightRightarrow left[begin{array}{ccc}x textgreater 5\ x textless -3end{array}right$


Ответ: $x in (-infty;-3)cup(5;+infty)$