\(x^2-2x\le 98-2x\\\leftrightarrow x^2-98\le 0\\\leftrightarrow (x-\sqrt{98})(x+\sqrt{98})\le 0\\\leftrightarrow \left[\begin{array}{1}\begin{cases}x-\sqrt{98}\ge 0\\x+\sqrt{98}\le 0\end{cases}\\\begin{cases}x-\sqrt{98}\le 0\\x+\sqrt{98}\ge 0\end{cases}\end{array}\right.\\\leftrightarrow \left[\begin{array}{1}\begin{cases}x\ge \sqrt{98}\\x\le -\sqrt{98}\end{cases}\\\begin{cases}x\le \sqrt{98}\\x\ge -\sqrt{98}\end{cases}\end{array}\right.\\\leftrightarrow-\sqrt{98}\le x\le \sqrt{98}\\mà \,\,x\in\Bbb N\\\to x\in\{0;1;2;3;4;5;6;7\}\)
