Brain Teasers
Golden Ratio
Which positive number is equal to its inverse plus one?
Answer
x =1/x + 1x=1.61803398875
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And how am I supposed to do that without a calculator? Having to use a calculator is no fun.
The complete answer wasn't printed.
x= (1+root5)/2. When written like this you don't need a calculator.
x= (1+root5)/2. When written like this you don't need a calculator.
Hey Mike, weren't you sitting in front of a big calculator when you read the problem? Here - let me help:
Start...Programs...Accessories...Calculator
Start...Programs...Accessories...Calculator
You left out
-0.61803398874989484820458683436564
(approximatly)
Or (1-root5)/2
-0.61803398874989484820458683436564
(approximatly)
Or (1-root5)/2
To cathalmccabe: the other negative solution of the quadratic is incorrect. The question asks for a positive number.
All the other reviewers have used big formulas I don't understand. Oh well, I stink at math : )
It's just the quadratic formula. But the braingle calculator doesn't do roots, so the decimal answer wasn't readily attainable to those of us too lazy to pull up the windows calc.
The slick thing is that it is also the result of convergence. Using braingel calculator, start [1][/], i.e. after clearing everything from memory push the one and then the divide. Next enter any guess. Then keep repeating following sequence of keys; [+][1][=][M+][1][/][MRC]...
The question asked for a number not an approximation, Thommo is the only person who has the correct answer. (It sort of gives it away in the title don't you think?)
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