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# Negative numbers

Multiplying a negative number by −1 gives its absolute value, e.g., ${\displaystyle |-{\frac {5}{8}}|=(-1)(-{\frac {5}{8}})={\frac {5}{8}}}$.
The square of a negative number ${\displaystyle x}$ is a positive number, and in fact ${\displaystyle x^{2}=(-x)^{2}}$; but the square root of that negative number is a purely imaginary number of the form ${\displaystyle i{\sqrt {|x|}}}$, where ${\displaystyle i}$ is the imaginary unit. For example, ${\displaystyle (-49)^{2}=2401}$, but ${\displaystyle {\sqrt {-49}}=7i}$.