## Algebra: A Combined Approach (4th Edition)

$x= ± \sqrt 11$
$5x^{2} = 55$ $x^{2} = \frac{55}{5}$ (Divide both sides by 5) $x^{2} = 11$ $x = ±\sqrt 11$ (Use the square root property) Check 1 : Let $x = \sqrt 11$ $5x^{2} = 55$ $5(\sqrt 11)^{2}$ could be 55 $5 \times 11$ could be 55 $55 = 55$ Hence, true. Check 2 : Let $x = -\sqrt 11$ $5x^{2} = 55$ $5(-\sqrt 11)^{2}$ could be 55 $5 \times 11$ could be 55 $55 = 55$ Hence, true. Therefore the solution set is ($\sqrt 11, -\sqrt 11$)