Roots Applications

The parabola shows the trajectory of a tennis ball that was hit with a tennis racket. What is the starting height of the tennis ball? (Click the picture to enlarge it)

• 3 feet - y-intercept

• 12 feet - vertex

• 1.5 seconds - vertex

• 3 seconds - x-intercept

The parabola shows the trajectory of a tennis ball that was hit with a tennis racket. How long di it take for the tennis ball to hit the ground? (Click the picture to enlarge it)

• 3 feet

• 12 feet

• 1.5 seconds

• 3 seconds

An object is launched upward and the height of the object is represented by the equation s(t) = –16t² + 64t + 80. How long does it take for the object to hit the ground after it has been launched?

• 2 seconds

• 5 seconds

• 80 seconds

• 0 seconds

If I want to find out when an object hits the ground, I should _________.

• Use x = (-b/2a) as my answer.

• Set my equation = 0 and solve.

• Replace x with 0 and evaluate.

• Find the y-coordinate of the vertex.

What is another word for zeros?

• y-intercepts

• roots

• vertex

• axis of symmetry

According to the graph, what is the root of the function g(x)?

• x=0

• y=0

• x=1

• y=-1

A lizard is jumping across the water in search of food. The equation h = -12t² + 6t models the lizard's height in feet above the water t seconds after he jumps. How long after jumping is he back on the water?

• 0.1 seconds

• 0.25 seconds

• 0.50 seconds

• 0.75 seconds

• 1 second

A raft is dropped from a helicopter 256 feet in the air above the ocean.  Its approximate height, h, after t seconds is given by the function h(t) = -16t² + 256.  How many seconds did it take the raft to hit the water? 

• -4

• 2

• 4

• 8

If the rocket was at a height of 5 feet at 1 seconds, at what other time was the rocket at a height of 5 feet?

• It was never at 5 feet again.

• 6 seconds

• 5 sconds

• 3 seconds

Solutions of a quadratic equation are also called

• roots

• x-intercepts

• zeros

• All of the above