The height of a ball when it is thrown off a cliff can be represented by the equation $h=45-7t-6t^2$, where $t$ is time in seconds. In how many seconds will the ball reach a height of 25 feet?
f(h)=45-7t-6t^2 Sub 25 for h and rearrange: 25 =45 - 7t - 6t^2 6t^2 + 7t - 45 + 25 6t^2 + 7t - 20 = 0 Solve for t using the Quadratic Formula t = 4 /3 = 1 1/3 seconds. t =- 5/2 (discard)
