Answer
Domain: All real numbers.
Range: $[-8,\infty)$
Work Step by Step
Given $$ T(z) = 0.2(z+6)^2-8.$$ The parabola opens upward as we can see from the graph. Its vertex gives the minimum point. The domain and range are given by:
Domain: All real numbers.
Range: $[-8,\infty)$.
