What is the value of b**2-a**2 when a=3, b=4
当a=3，b=4时b**2-a**2的值是多少
<gadget id="calculator">4 ** 2</gadget>
<output>16</output>

<gadget id="calculator">3 ** 2</gadget>
<output>9</output>

<gadget id="calculator">16 - 9</gadget>
<output>7</output>

<result>7</result>