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9 votes
9 votes
Write the number as the product of a real number and i
- √( - 20)

User Tomdarkness
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1 Answer

17 votes
17 votes

Take into account that 20 = 5*4 = 5*2^2.

Furthermore, -20 = (-1)*20 and i = √-1

Hence, you have:


-\sqrt[]{20}=-\sqrt[]{(-1)(20)}=-\sqrt[]{(-1)(5\cdot2^2)}=-2\sqrt[]{5}\sqrt[]{-1}=-2\sqrt[]{5}i

Then answer is -2√5*i

User Petras Purlys
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2.9k points