Expand menu menu_open Minimize Start chapters Home History history History expand_more
{{ item.displayTitle }}
navigate_next
No history yet!
Progress & Statistics equalizer Progress expand_more
Student
navigate_next
Teacher
navigate_next
{{ filterOption.label }}
{{ item.displayTitle }}
{{ item.subject.displayTitle }}
arrow_forward
No results
{{ searchError }}
search
menu_open
{{ courseTrack.displayTitle }}
{{ statistics.percent }}% Sign in to view progress
{{ printedBook.courseTrack.name }} {{ printedBook.name }}
search Use offline Tools apps
Login account_circle menu_open

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=3x=-3-x27x+4=0x2+7x4=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}