<u><span>a3 + 27 </span></u><span> =<u>a^3+2^3 </u><u> </u>=<u>(a+3)(a^2-3a+9)</u> = a+3</span>
<span><span> (a+3)^2-9a a^2+6a+9-9a a^2-3a+9</span></span>