Quadratic functions. Did I do it right?

1) The graph is opening upwards

2) Axis of symmetry is x=-2

3) Vertex: (-2, 1) minimum y=1

4) y intercept is (0, 9)

5) domain: x|x ∈ R (All real numbers)

6) Range y|y ≥ 1

h(t) = 210 – 15t models the altitude of a hot air balloon over time t, in minutes

means that at time t min, the height h of the balloon is 210-15t     (units)

for example,

at time t=1 min, the height of the balloon is 210-15*1=195 (units)

at time t=2 min, the height of the balloon is 210-15*2=210-30=180   (units)

thus, h(10) is the height of the balloon at time t=10 min,

h(10)=210-15*10=210-150=60

step-by-step explanation: