# [racket] HTDP 2nd edition exercise 4.2.3 - floating point issues

equation 2 is 2n^2 = 102 so I implement like this:
;; equation3 : number -> boolean
;; to determine whether n is a solution for 2n^2 = 102
(define (equation3 n)
(= (* 2 n n) 102))
And my answer is the same as per the online answer. so great.
But how can I check a valid answer.
Eg if I do:
(equation3 (sqrt 51))
>*false
*
same using - square root 51.
How can I fix this? Is the only way to do a range check? Eg have some
sort of tolerance - eg between 0.01 above and below answer? Any other
ideas?
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