jmc

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.

Accepted Answer

Setting y to zero, we find the following: align* 0& = -16t^2 + 26t + 105 & = 16t^2 - 26t - 105 & = (8t + 15)(2t - 7) align*As t must be positive, we can see that t = 72 = 3.5.