The function f is defined by $${f}({x})=\sqrt x-{10}$$ for all positive numbers x. If $$u = f(t)$$ for some positive numbers $$t$$ and $$u$$. What is t in terms of $$u$$?
-
A$$\sqrt{u+10}$$
-
B$$(\sqrt{u}+{10})^{2}$$
-
C$${\sqrt{{u}^{2}+10}}$$
-
D$$({u}+{10})^{2}$$
-
E$$({u}^{2}+{10})^{2}$$