I just don’t know how to do it all. I got is in the attachment file. I know i need to use derivative but this function is just to massive for me.
zada.bmp (1.15 MB)
RegionPlot3D[0<=1/4(1?a?b?c)&&
1/4(1?a?b?c)<=1&&
0<=1/4(1+a+b?c)&&
1/4(1+a+b?c)<=1&&
0<=1/4(1+a?b+c)&&
1/4(1+a?b+c)<=1&&
0<=1/4(1?a+b+c)&&
1/4(1?a+b+c)<=1&&
a^2<b^2&&b^2<c^2,{a,-1,1},{b,-1,1},{c,-1,1},
AxesLabel->{"a","b","c"}, PlotPoints->50]
f[x_] := (Sqrt[1 - a + (b + c) (c + b x - c x) -
Sqrt[(b + 2 c - a c)^2 - (b^2 - c^2) (-3 + 4 a - a^2 + b^2 - c^2) x + (b^2 - c^2)^2 x^2]] +
Sqrt[1 - a + (b + c) (c + b x - c x) +
Sqrt[(b + 2 c - a c)^2 - (b^2 - c^2) (-3 + 4 a - a^2 + b^2 - c^2) x + (b^2 - c^2)^2 x^2]] +
Sqrt[1 + a - (b - c) (c - b x - c x) -
Sqrt[(b - 2 c - a c)^2 - (b^2 - c^2) (-3 - 4 a - a^2 + b^2 - c^2) x + (b^2 - c^2)^2 x^2]] +
Sqrt[1 + a - (b - c) (c - b x - c x) +
Sqrt[(b - 2 c - a c)^2 - (b^2 - c^2) (-3 - 4 a - a^2 + b^2 - c^2) x + (b^2 - c^2)^2 x^2]])^2;