Question

An object is launched from a platform. It's height is meters is modeled by: h(x)= -5(x+1)(x-9) where x represents the time in schools after the launch. How many seconds after launch will the object hit the ground

Answer 1

Answer: 9 seconds

Explanation:

When the object hit the ground,

Height h = 0

Therefore,

h(x)= -5(x+1)(x-9) = 0

0 = -5(x+1)(x-9)

Open the bracket

0 = (-5x - 5)( x - 9)

0 = -5x^2 + 45x - 5x + 45

0 = -5x^2 + 40x + 45

Divide all by -5

0 = x^2 - 8x - 9

Factorizing the equation gives

(x + 1)(x- 9)

x = -1 or 9

Since Time can't be negative

Therefore, the time seconds after launch the object will hit the ground is 9 seconds