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

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

%S 6,9,8,6,5,6,7,0,5,5,3,2,3,6,0,2,6,2,8,3,7,9,0,4,6,5,8,4,0,1,6,6,0,3,

%T 2,2,9,3,5,4,5,6,2,1,2,5,9,4,7,3,1,4,2,0,8,0,6,8,3,5,4,7,3,7,3,9,6,9,

%U 1,5,0,7,3,5,3,1,4,2,4,1,0,5,2,4,8,3,1,7,4,7,2,5,2,1,3,2,7,8,4

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

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

%e least x: -0.6986567055323602628379046584016603229...

%e greatest x: 0.41073056810531967884261632168842932...

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

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

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

%t r1 = x /. FindRoot[f[x] == g[x], {x, -.7, -0.6}, WorkingPrecision -> 110]

%t RealDigits[r1] (* A198214 *)

%t r2 = x /. FindRoot[f[x] == g[x], {x, 4.1, 4.2}, WorkingPrecision -> 110]

%t RealDigits[r2] (* A198215 *)

%Y Cf. A197737.

%K nonn,cons

%O 0,1

%A _Clark Kimberling_, Oct 22 2011