perplexus.info :: Just Math : A repeating irrational number?

A repeating irrational number? (Posted on 2005-06-06)

Can you explain why the fourth root of 9.1 is practically the same as 33/19? You shouldn't use even a calculator!

See The Solution Submitted by e.g.

Rating: 3.1667 (6 votes)

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I has to use a calculator a little.

| Comment 1 of 8

(9.1)^(1/4) ~ 33/19

9.1 ~ (33/19)^4

91/10 ~ 33^4/19^4

1 ~ (10 * 33^4)/(91 * 19^4) [calulator comes out]

1 ~ 11859210 / 11859211

So I guess the reason is these two consectutive large numbers each contain fourth powers as factors.

Posted by Jer on 2005-06-06 18:19:57

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