A package drops. The height of the package above the ground at any time is modeled by the function

h(t)= -5t2-30x + 675, where h(t) is the height in meters, and t is the time in seconds. How long will it take the package to hit the ground? Please show your work and explain what you did because I want to learn it and not just copy.

h(t)= -5t2-30x + 675, where h(t) is the height in meters, and t is the time in seconds. How long will it take the package to hit the ground? Please show your work and explain what you did because I want to learn it and not just copy.

0 = height at ground level

0 = -5t2- 30t + 675

-5t2- 30t + 675 = 0 {just switched it around, no big deal}

-5(t2+ 6t - 135) = 0 {factor -5 out}

-5(t + 15)(t - 9) = 0 {factor into 2 binomials}

t + 15 = 0 or t - 9 = 0 {set each factor equal to 0}

t = -15 or t = 9 {time cannot be negative}

t = 9 seconds

- Algebra House

0 = -5t2- 30t + 675

-5t2- 30t + 675 = 0 {just switched it around, no big deal}

-5(t2+ 6t - 135) = 0 {factor -5 out}

-5(t + 15)(t - 9) = 0 {factor into 2 binomials}

t + 15 = 0 or t - 9 = 0 {set each factor equal to 0}

t = -15 or t = 9 {time cannot be negative}

t = 9 seconds

- Algebra House