Here a = x<span> and b = </span>8<span>, thus if </span>x<span> + </span>8<span> is a </span>factor<span>, then </span>x<span> - </span>8<span> is also a </span>factor.. (x<span> + </span>8)(x<span>- </span>8<span>) <-- expand this out using </span>difference of squares<span> rules.</span>