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

%I #5 Mar 30 2012 18:57:53

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

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

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

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

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

%e least x: -1.1690226923053929102101002288527830...

%e greatest x: 0.89565238135842890121817647213537...

%t a = 2; 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, -1.17, -1.16}, WorkingPrecision -> 110]

%t RealDigits[r1](* A198118 *)

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

%t RealDigits[r2](* A198119 *)

%Y Cf. A197737.

%K nonn,cons

%O 1,3

%A _Clark Kimberling_, Oct 21 2011