If 3x-5 and (1/7) are reciprocals, what is the value of (1/2)x**2-(1/8)x**3?
如果3x-5与(1/7)互为倒数，那么(1/2)x**2-(1/8)x**3的值是多少．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">5 + 7</gadget>
<output>12</output>

<gadget id="calculator">12 / 3</gadget>
<output>4</output>

<gadget id="calculator">4 ** 2</gadget>
<output>16</output>

<gadget id="calculator">(1/2) * 16</gadget>
<output>8</output>

<gadget id="calculator">1 / 8</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">4 ** 3</gadget>
<output>64</output>

<gadget id="calculator">(1/8) * 64</gadget>
<output>8</output>

<gadget id="calculator">8 - 8</gadget>
<output>0</output>

<result>0</result>