Math Is Fun Forum

PatternMan

Member

Registered: 2014-03-08

Posts: 199

Complex number

√-20
= √20 i
= √4 x √5 i
= 2 x √5 i
= 2√5i

The textbook said the answer to this is √20i. did I misunderstand something?

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"School conditions you to reject your own judgement and experiences. The facts are in the textbook. Memorize and follow the rules. What they don't tell you is the people that discovered the facts and wrote the textbooks are people like you and me."

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Complex number

Hi;

Your answer is correct and so is the books but it is not simplified.

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

PatternMan

Member

Registered: 2014-03-08

Posts: 199

Re: Complex number

Thanks. I was just confused because they simplified everything else.

---

"School conditions you to reject your own judgement and experiences. The facts are in the textbook. Memorize and follow the rules. What they don't tell you is the people that discovered the facts and wrote the textbooks are people like you and me."

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Complex number

Hi;

You are welcome.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.