Answer
a. $m(x)=3\sqrt{x+10}$
b. The domain is: $[-10;0)$
c. $m(-1)=9$
Work Step by Step
a. The function, that is defined by $m=3u$ is equivalent to:
$m(x)=3u(x)$, here it means:
$m(x)=3\sqrt{x+10}$
b. The domain is the same as for $u(x)$, as the expression under the root sign does not change.
The domain is: $[-10;0)$
c. $m(-1)=3\sqrt{-1+10}=3\times \sqrt{9}=3\times3=9$
