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Decimal expansion of least x having 3*x^2+x=4*cos(x).
3

%I #5 Mar 30 2012 18:57:54

%S 1,0,1,9,0,9,2,5,0,2,8,1,5,4,1,8,0,6,7,9,8,4,1,7,9,1,2,6,0,8,9,8,5,9,

%T 0,3,6,9,6,2,2,3,0,4,4,2,0,6,4,4,7,2,2,9,4,8,2,0,6,4,1,7,4,3,6,4,6,3,

%U 9,2,2,2,2,2,8,3,2,4,7,7,8,9,1,6,3,7,3,7,3,9,3,4,6,3,8,0,8,7,1

%N Decimal expansion of least x having 3*x^2+x=4*cos(x).

%C See A197737 for a guide to related sequences. The Mathematica program includes a graph.

%e least x: -1.0190925028154180679841791260898590369...

%e greatest x: 0.807678482427210650918057213078375663...

%t a = 3; b = 1; c = 4;

%t f[x_] := a*x^2 + b*x; g[x_] := c*Cos[x]

%t Plot[{f[x], g[x]}, {x, -2, 1}]

%t r1 = x /. FindRoot[f[x] == g[x], {x, -1.1, -1}, WorkingPrecision -> 110]

%t RealDigits[r1] (* A198220 *)

%t r2 = x /. FindRoot[f[x] == g[x], {x, .8, .9}, WorkingPrecision -> 110]

%t RealDigits[r2] (* A198221 *)

%Y Cf. A197737.

%K nonn,cons

%O 1,4

%A _Clark Kimberling_, Oct 22 2011