Sqrt(-4).sqrt(-9)

Regarding the problem sqrt(-4).sqrt(-9).

I think that the sqrt(-4) is 2i or -2i and likewise for sqrt(-9). This means that the solution to the problem is not unique and that -2i times 3i would make 6 a correct answer also. What do you say to this idea.

Easy Math Editor

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Comments

$\sqrt{4}=|2|$ and not $-2$ .

Note that $\sqrt{-4} = \sqrt{4} \times \sqrt{-1} = 2\times i$ and similarly for $\sqrt{-9}=9i$ . Hence the answer would be $2i \times 3i = -6$

Vilakshan Gupta - 3 years, 5 months ago

Is there a good reason for discounting -i as a possible sqrt(-1)? Is -2+i positive or negative?

Ron C

Ron Cole - 3 years, 5 months ago

There is no reason to it. $i$ is defined as $\sqrt{-1}$ .

$-i=-\sqrt{-1}$

There is nothing positive/negative in domain of complex numbers.So $-2+i$ is neither positive nor negative.

Vilakshan Gupta - 3 years, 5 months ago

Math	Appears as
Remember to wrap math in `\(` ... `\)` or `\[` ... `\]` to ensure proper formatting.
`2 \times 3`	$2 \times 3$
`2^{34}`	$2^{34}$
`a_{i-1}`	$a_{i-1}$
`\frac{2}{3}`	$\frac{2}{3}$
`\sqrt{2}`	$\sqrt{2}$
`\sum_{i=1}^3`	$\sum_{i=1}^3$
`\sin \theta`	$\sin \theta$
`\boxed{123}`	$\boxed{123}$