\[\frac{\left(-b\right) + \sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c}}{2 \cdot a}\]
\frac{\left(-b\right) + \sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c}}{2 \cdot a}
double f(double a, double b, double c) {
        double r6279 = b;
        double r6280 = -r6279;
        double r6281 = r6279 * r6279;
        double r6282 = 4.0;
        double r6283 = a;
        double r6284 = r6282 * r6283;
        double r6285 = c;
        double r6286 = r6284 * r6285;
        double r6287 = r6281 - r6286;
        double r6288 = sqrt(r6287);
        double r6289 = r6280 + r6288;
        double r6290 = 2.0;
        double r6291 = r6290 * r6283;
        double r6292 = r6289 / r6291;
        return r6292;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2020045 
(FPCore (a b c)
  :name "Quadratic roots, full range"
  :precision binary64
  (/ (+ (- b) (sqrt (- (* b b) (* (* 4 a) c)))) (* 2 a)))

Backtrace

hash-ref: no value found for key key: '(* #<enode 5(724)> #<enode 687(687)>)LC
for-loop/data/pavpan/nightlies/herbie/simplify-regraph-rebuilding/regraph/egraph.rkt2706
update-leader!/data/pavpan/nightlies/herbie/simplify-regraph-rebuilding/regraph/egraph.rkt2650
for-loop/data/pavpan/nightlies/herbie/simplify-regraph-rebuilding/regraph/main.rkt772
prune-phase/data/pavpan/nightlies/herbie/simplify-regraph-rebuilding/regraph/main.rkt740
for-loop/data/pavpan/nightlies/herbie/simplify-upwards-no-duplicates/src/core/simplify.rkt804
for-loop/data/pavpan/nightlies/herbie/simplify-upwards-no-duplicates/src/core/simplify.rkt762
(unnamed)/data/pavpan/nightlies/herbie/simplify-upwards-no-duplicates/src/core/simplify.rkt560
(unnamed)/data/pavpan/nightlies/herbie/simplify-upwards-no-duplicates/src/core/simplify.rkt380
simplify!/data/pavpan/nightlies/herbie/simplify-upwards-no-duplicates/src/mainloop.rkt2240
run-iter!/data/pavpan/nightlies/herbie/simplify-upwards-no-duplicates/src/mainloop.rkt3270
for-loop/data/pavpan/nightlies/herbie/simplify-upwards-no-duplicates/src/mainloop.rkt3654
run-improve47/data/pavpan/nightlies/herbie/simplify-upwards-no-duplicates/src/mainloop.rkt3460
.../more-scheme.rkt:261:28unknown
run/opt/racket-7.5/share/pkgs/profile-lib/main.rkt392
profile-thunk16/opt/racket-7.5/share/pkgs/profile-lib/main.rkt90
(unnamed)/opt/racket-7.5/collects/racket/private/more-scheme.rkt26128