Ssolve y=2x+4. y=-3-1

Which function is represented by the graph

Astuntman jumping off a 20-m-high building is modeled by the equation h=20-5t^2, where t is the same in seconds. a high-speed camera is ready to film him between 15m and 10m above the ground. for which interval of time should the camera film him?

[10 points, algebra 2]according to my answer key the restrictions are -1 and 4. but why not positive 1?