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43 votes
Simplify: ✓- 72 O A - 6iva O B. 6iv 2 O c. 5i/3 OD. – 517 3

Simplify: ✓- 72 O A - 6iva O B. 6iv 2 O c. 5i/3 OD. – 517 3-example-1
User Slawomir Dziuba
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1 Answer

26 votes
26 votes

We want to simplify the following expression


\sqrt[]{\text{ -72}}

To do so we will use the following properties


\sqrt[]{a\cdot b}=\sqrt[]{a}\cdot\sqrt[]{b}

and


\sqrt[]{\text{ -1}}=i

So we have that


\sqrt[]{\text{ -72}}=\sqrt[]{\text{ -1}\cdot72}=\sqrt[]{\text{ -1}}\cdot\sqrt[]{72}=\sqrt[]{72}i=\sqrt[]{8\cdot9}i=\sqrt[]{8}\cdot\sqrt[]{9}i=\pm3\cdot\sqrt[]{8}i=\pm3\cdot\sqrt[]{4\cdot2}i=\pm3\sqrt[]{4}\sqrt[]{2}i

which is equal to


\pm3\cdot2\sqrt[]{2}i=\pm6\sqrt[]{2}i

so options A and B are correct

User Boldewyn
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