x=.

L2[x_]:=10(((x-121)(x-144))/((100-121)(100-144)))  + 11 (((x-100)(x-144))/((121-100)(121-144)))+12(((x-100)(x-121))/((144-100)(144-121)))

L2[x]

L2[115.]

Sqrt[115.]

Оценка на грешката:

f[x_]:=Sqrt[x]
Plot[Abs[f'''[x]],{x,100,144}]

M3=Abs[f'''[100]]

R2[x_]:=(M3/(3!))Abs[(x-100)(x-121)(x-144)]
R2[115.]