dxu comments on Innate Mathematical Ability - Less Wrong

40 Post author: JonahSinick 18 February 2015 11:11AM

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Comment author: Luke_A_Somers 19 February 2015 02:11:59AM *  3 points [-]

Well, I rather quickly identified the straightforward algebraic way of solving it.

x = 1 + 1/y

y = 2 + 1/y

yy - 2y -1 = 0

Having reduced it to the quadratic formula and a substitution, and lacking a pen and paper, I did not pursue further at the time. Now I'm curious. Let's add 2 to complete the square...

yy - 2y + 1= 2 = (y-1)(y-1)

y = 1 +/- √2

Since X is 1 less than y, these yield X = +/- √2.

I don't find this obvious, even in retrospect.

Comment author: dxu 19 February 2015 03:32:52AM 0 points [-]

I spent around twenty seconds looking at it and gave up. Then I came back fifteen minutes later, spent an additional twenty seconds looking at it and figured it out. I'm not sure what that says about my intelligence/pattern-recognition skills, but it probably says bad things about my conscientiousness.