login
Decimal expansion of x>0 satisfying x^2+4*cos(x)=4.
2

%I #5 Mar 30 2012 18:57:56

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

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

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

%N Decimal expansion of x>0 satisfying x^2+4*cos(x)=4.

%C See A198755 for a guide to related sequences. The Mathematica program includes a graph.

%e x=2.7831147565030203006399227292369585185988130...

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

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

%t Plot[{f[x], g[x]}, {x, -3, 3}, {AxesOrigin -> {0, 0}}]

%t r = x /. FindRoot[f[x] == g[x], {x, 2.7, 2.8}, WorkingPrecision -> 110]

%t RealDigits[r] (* A198815 *)

%Y Cf. A198755.

%K nonn,cons

%O 1,1

%A _Clark Kimberling_, Oct 30 2011