4.( - 1/2)^3 - 2.( - 1/2)^2+ 3.( - 1/2) + 1

Lời giải:

\(4\,.\,{\left( { - \frac{1}{2}} \right)^3} - 2.{\left( { - \frac{1}{2}} \right)^2} + 3\,.\,\left( { - \frac{1}{2}} \right) + 1\).

\( = 4\,.\,\frac{{ - 1}}{8} - 2.\frac{1}{4} + \frac{{ - 3}}{2} + 1\)

\( = \frac{{ - 1}}{2} - \frac{1}{2} + \frac{{ - 3}}{2} + 1\)

\( = - 1 + 1 + \frac{{ - 3}}{2}\)

\( = 0 + \frac{{ - 3}}{2} = \frac{{ - 3}}{2}\).