<u>We</u><u> </u><u>can</u><u> </u><u>write</u><u> </u><u>9</u><u> </u><u>as</u><u> </u><u>3</u><u>²</u><u> </u>(Why?) because it forms identity a² - b² = (a + b) (a - b) .
This gives the information that either,
<u>x - 3 = 0 or x + 3 = </u><u>0</u>
<u>So</u><u>,</u><u> </u>x = 3 or x = -3
<em>Hope it helps,<u> you may ask if you have any </u><u>co</u></em>nfusions ^-^