What is the sum of the polynomials?

(–x2 + 9) + (–3x2 – 11x + 4)

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?

Two cyclists 84 miles apart start riding toward each other at the same. one cycles 2 times as fast as the other. if they meet 4 hours later, what is the speed (in mi/h) of the faster cyclist?

Need 50 will mark brainliest answer. find the lengths of all the sides and the measures of the angles.