If a+b=6, a*b=4 and (a+b)**2=a**2+2ab+b**2 is known, then how much is a**2+b**2=.
若a+b=6，a*b=4且已知(a+b)**2=a**2+2ab+b**2则a**2+b**2=多少．
<gadget id="calculator">6 ** 2</gadget>
<output>36</output>

<gadget id="calculator">2 * 4</gadget>
<output>8</output>

<gadget id="calculator">36 - 8</gadget>
<output>28</output>

<result>28</result>