Question

The equation y = -16t^2 + 26t + 105 describes the height (in feet) of a ball tossed up in the air at 26 feet per second from a height of 105 feet above the ground. In how many seconds will the ball hit the ground? Express your answer as a decimal rounded to the nearest tenth.

Answer 1

The idea is to replace y with 0 and solve for t through the use of the quadratic formula. Check out the attached image for the steps on the quadratic formula.

The final answer is 3.5

Note: there are two possible answers when you solve for t; however, the negative t value is ignored as negative time values make no sense.