Today’s topic is inequalities, expressions like \(a\geq b\), or \(a>b\). There are certain rules for operating inequalities: one can subtract the same number from both sides of the inequality, namely if \(a\geq b\), then \(a-b \geq 0\). If \(a \geq b\) and \(b\geq c\), then \(a\geq c\). If a number \(c\geq 0\), then from \(a\geq b\) it follows that \(ac \geq bc\). However, in case of multiplication by a negative number \(c\leq 0\), the inequality sign reverses: from \(a\geq b\) it follows that \(ac \leq bc\). One should also remember that the square of any real number is non-negative.