ข้อสอบคณิต O-NET - 2561

$$\begin{gathered} \mathrm{จากแต่ละตัวเลือก} \\ 1. f\left(-6\right) = \left|-6-5\right|-5 \\ = 11-5 \\ = 6 \to \mathrm{ถูก} \\ 2. f\left(-5\right) = \left|-5-5\right|-5 \\ = 10-5 \\ = 5 \to \mathrm{ถูก} \end{gathered}$$

$$\begin{gathered} 3. f\left(0\right) = \left|0-5\right|-5 \\ = 5-5 \\ = 0 \to \mathrm{ถูก} \\ 4. f\left(5\right) = \left|5-5\right|-5 \\ = 0-5 \\ = -5 \to \mathrm{ถูก} \end{gathered}$$

$$\begin{gathered} 5. f\left(6\right) = \left|6-5\right|-5 \\ = 1-5 \\ = -4 \to \mathrm{ผิด} \\ \mathrm{ดังนั้น} \mathrm{ตอบข้อ} 5 \end{gathered}$$