## College Algebra (10th Edition)

The Domain is {All real numbers, $t \ge 4, t \ne7$}
To find the domain, we must set the denominator equal to 0, and solve for $t$. $$3t-21=0$$ $$3(t-7)=0$$ $$t\ne7$$ It is important that we do not divide the whole equation by 3 in the first step. We instead need to factor out a 3. Also, t must be greater than or equal to 4, or the value inside the radical would be negative.