\[(a + b)^{3}\text{\ \ \ }\]
\[\text{\ a} = - 1,6;\text{\ \ }\ b = 2,1:\]
\[( - 1,6 + 2,1)^{3} = 0,5^{3} = 0,125.\]
\[a = 1,4;\ b = 2,6:\]
\[(1,4 + 2,6)^{3} = 4^{3} = 64.\]