Используем свойства степеней: (am)n = am*n и am ⋅ an = am+n.
11⁻⁵ ⋅ (11³) ² = 11⁻⁵ ⋅ 113*2 = 11⁻⁵ ⋅ 116.
11⁻⁵ ⋅ 116 = 11-5+6 = 111 = 11.