f[x_]:=((Tan[x+3])/((x^2)-4))
Plot[f[x],{x,-10,10}]

f[x_]:=Tan[x+3]
Plot[f[x],{x,-10,10}]

Plot[1/x,{x,-10,10}]

Plot[1/((x^2)-4),{x,-5,5}]

f[x_]:=((Tan[x+3])/((x^2)-4))
Plot[f[x],{x,-1,1}]

f[-1.]

f[1]

%//N

(* дефиниране на функция: *)
f[x_]:=((Tan[x+3])/((x^2)-4))
a=-1.;
b=1;
ne=(10^(-3));eps=1;
For[n=0,eps>ne,n++,
m=((a+b)/2);eps = ((b-a)/2);
Print["n = ",n, " (Subscript[a, n]) = ",a, " (Subscript[b, n]) = ",b, " (Subscript[m, n]) = ",m , " fm= ", f[m], " (Subscript[ϵ, n]) = ",eps];
If[f[m]>0,a=m,b=m]
]

Log2[((1-(-1))/(10^(-12)))]-1

%//N