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 A199170 Decimal expansion of x<0 satisfying x^2+x*cos(x)=1. 54
 1, 1, 9, 8, 3, 5, 9, 8, 4, 4, 5, 1, 8, 6, 6, 0, 2, 6, 8, 2, 6, 5, 0, 2, 1, 6, 0, 3, 4, 3, 0, 3, 0, 8, 9, 8, 9, 2, 7, 2, 6, 8, 0, 9, 3, 5, 8, 7, 4, 8, 2, 5, 6, 9, 0, 1, 4, 4, 4, 9, 2, 3, 8, 6, 8, 6, 4, 2, 7, 1, 7, 6, 1, 4, 9, 7, 1, 9, 1, 2, 5, 5, 9, 1, 7, 1, 4, 2, 8, 9, 1, 6, 9, 7, 2, 0, 9, 5, 4 (list; constant; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS For many choices of a,b,c, there are exactly two numbers x satisfying a*x^2+b*x*cos(x)=c. Guide to related sequences, with graphs included in Mathematica programs: a.... b.... c.... x 1.... 1.... 1.... A199170, A199171 1.... 1.... 2.... A199172, A199173 1.... 1.... 3.... A199174, A199175 1.... 2.... 1.... A199176, A199177 1.... 2.... 2.... A199178, A199179 1.... 2.... 3.... A199180, A199181 1.... 3.... 1.... A199182, A199183 1.... 3.... 2.... A199184, A199185 1.... 3.... 3.... A199186, A199187 2.... 1.... 1.... A199188, A199189 2.... 1.... 2.... A199265, A199266 2.... 1.... 3.... A199267, A199268 2.... 2.... 1.... A199269, A199270 2.... 2.... 3.... A199271, A199272 2.... 3.... 1.... A199273, A199274 2.... 3.... 2.... A199275, A199276 2.... 3.... 3.... A199277, A199278 3.... 1.... 1.... A199279, A199280 3.... 1.... 2.... A199281, A199282 3.... 1.... 3.... A199283, A199284 3.... 2.... 1.... A199285, A199286 3.... 2.... 2.... A199287, A199288 3.... 2.... 3.... A199289, A199290 3.... 3.... 1.... A199291, A199292 3.... 3.... 2.... A199293, A199294 Suppose that f(x,u,v) is a function of three real variables and that g(u,v) is a function defined implicitly by f(g(u,v),u,v)=0.  We call the graph of z=g(u,v) an implicit surface of f. For an example related to A199170, take f(x,u,v)=x^2+u*xcos(x)-v and g(u,v) = a nonzero solution x of f(x,u,v)=0.  If there is more than one nonzero solution, care must be taken to ensure that the resulting function g(u,v) is single-valued and continuous.  A portion of an implicit surface is plotted by Program 2 in the Mathematica section. LINKS EXAMPLE negative: -1.19835984451866026826502160343030898927268... positive:  0.685174133854503187895211530638458709591... MATHEMATICA (* Program 1:  A199170 and A199171 *) a = 1; b = 1; c = 1; f[x_] := a*x^2 + b*x*Cos[x]; g[x_] := c Plot[{f[x], g[x]}, {x, -2 Pi, 2 Pi}, {AxesOrigin -> {0, 0}}] r = x /. FindRoot[f[x] == g[x], {x, -1.2, -1.1}, WorkingPrecision -> 110] RealDigits[r]  (* A199170 *) r = x /. FindRoot[f[x] == g[x], {x, .68, .69}, WorkingPrecision -> 110] RealDigits[r]  (* A199171 *) (* Program 2: implicit surface of x^2+u*x*cos(x)=v *) f[{x_, u_, v_}] := x^2 + u*x*Cos[x] - v; t = Table[{u, v, x /. FindRoot[f[{x, u, v}] == 0, {x, 0, 1}]}, {u, 0,     1.9}, {v, u, 600}]; ListPlot3D[Flatten[t, 1]]  (* for A199170 *) CROSSREFS Cf. A199171, A197737, A198414, A198755, A198866. Sequence in context: A255251 A224236 A118427 * A155532 A086306 A094139 Adjacent sequences:  A199167 A199168 A199169 * A199171 A199172 A199173 KEYWORD nonn,cons AUTHOR Clark Kimberling, Nov 03 2011 STATUS approved

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Last modified December 8 14:38 EST 2019. Contains 329865 sequences. (Running on oeis4.)