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Change signs

Theory

Change signs

An equation can be rewritten by changing all signs. This is equivalent to multiply or divide both sides by -1.\text{-}1. -x=3⇔x=-3-x2−7x+4=0⇔x2+7x−4=0\begin{aligned} \text{-} x=3 \quad &\Leftrightarrow \quad x=\text{-} 3 \\ \text{-} x^2 -7x+4=0 \quad &\Leftrightarrow \quad x^2+7x-4=0 \end{aligned}