### Home > INT3 > Chapter 6 > Lesson 6.3.1 > Problem6-78

6-78.

Solve $2 \sqrt { 21 - x } - \sqrt { 3 x - 6 } = 5$ and check your solution.

Place one radical on each side of the equation, then square.

$2\sqrt{21-x}=5+\sqrt{3x-6}$
$( 2\sqrt{21-x})^2=(5+\sqrt{3x-6})^2$

You will still have a radical after this step. Isolate it and square again.

$x = 5$, remember to check your solution.