ข้อสอบคณิต O-NET - 2553

$$\begin{gathered} \mathrm{จากโจทย์} \mathrm{แต่ละข้อ} \\ 1) {\left(-1\right)}^0 = 1 \\ 2) {\left(-1\right)}^{0.2} = {\left(-1\right)}^{\frac{2}{10}} \\ = {\left(-1\right)}^{\frac{1}{5}} \\ = \sqrt[5]{-1} \\ = -1 \end{gathered}$$

$$\begin{gathered} 3) {\left(-1\right)}^{0.4} = {\left(-1\right)}^{\frac{4}{10}} \\ = {\left(-1\right)}^{\frac{2}{5}} \\ = \sqrt[5]{{\left(-1\right)}^2} \\ = \sqrt[5]{1} \\ = 1 \end{gathered}$$

$$\begin{gathered} 4) {\left(-1\right)}^{0.8} = {\left(-1\right)}^{\frac{8}{10}} \\ = {\left(-1\right)}^{\frac{4}{5}} \\ = \sqrt[5]{{\left(-1\right)}^4} \\ = \sqrt[5]{1} \\ = 1 \end{gathered}$$

$\mathrm{ดังนั้น} \mathrm{ตอบ} \mathrm{ข้อ} 2$