Question 152648
It looks a lot harder than it is. Any time an equation has two square roots with the same thing under them, we can just multiply them together:
{{{sqrt(x-6)*sqrt(x-6) = 15}}}
{{{(sqrt(x-6))^2 = 15}}}
{{{x-6=15}}}
<br>When you square the square root of anything, the square and the square root basically cancel each other out. Now it's a lot easier to solve:
{{{x-6=15}}}
{{{x-6+6=15+6}}}
{{{x=21}}}
<br>Therefore, the answer is b.