- #1

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There a simple math example that I am confused ##(\sqrt {-4})^2##

Theres two ways to think

1-##\sqrt {-4}=2i## so ##(2i)^2=4i^2## which its ##-4##

2-##\sqrt {-4}##.##\sqrt {-4}##=##\sqrt {-4.-4}=\sqrt{16} =4##

I think second one is wrong but I couldn't prove how, but I think its cause ##\sqrt {-4}## is not "reel" number so we cannot take them into one square root

Theres two ways to think

1-##\sqrt {-4}=2i## so ##(2i)^2=4i^2## which its ##-4##

2-##\sqrt {-4}##.##\sqrt {-4}##=##\sqrt {-4.-4}=\sqrt{16} =4##

I think second one is wrong but I couldn't prove how, but I think its cause ##\sqrt {-4}## is not "reel" number so we cannot take them into one square root

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