Algebra

posted by .

A ball is thrown into the air. The height h, in feet, of the ball can be modeled by the equation h= -16t^2+20t+6, where t is the time, in seconds, the ball is in the air. When will the ball hit the ground?

first should I use x= -b/2a?

• Algebra -

-2(8t^2 -10t -6) = 0

-2(2t -3) (4t +1) = 0

2t -3 = 0

2t-3 + 3 = 0 + 3

2t = 3

t = 3/2 second

• Algebra -

Solve the equation

-16t^2+20t+6 = 0
will give you the times that the ball is on the ground. The negative root accounts for the fact that the ball is 6 feet above ground at t=0.
I get t=3/2 and t=-1/4

• Algebra -

x = -b/2a will give you the vertex. That will tell you how high the ball went if you plug it in and evaluate h.

• Algebra -

Thank you to all

Similar Questions

1. algebra

When thrown into the air from the top of a 50 ft building, a ball’s height, S, at time t can be found by S(t) = -16t^2 + 32t + 50. When t = 1, s = -16(1)^2 + 32(1) + 50 = 66. This implies that after 1 second, the height of the ball …
2. college algebra

When a ball is thrown up into the air, it makes the shape of a parabola. The equation S= -16t^2 + v*t + k gives the height of the ball at any time, t in seconds, where “v” is the initial velocity (speed) in ft/sec and “k” is …
3. algebra

when a ball is thrown up into the air it makes the shape of a parabola the equation s=-16t^2+v*t+k gives the height nof the ball at any time t in seconds where "v" is the initial velocity (speed)in ft/sec and "k" is the initial height …
4. ALGEBRA 1

The height h is the time of seconds that the ball has been in the air with an initial vertical velocity of 48 feet per second from a height of 5 feet above the ground is given by the equation h=-16t^2 + 48t + 5 where t is the time …
5. algebra

When a ball is thrown in the air, the height h of a ball in feet t seconds after the ball is thrown in the air, is given by the equation height = 25t–16t² Use the quadratic equation to determine how many seconds goes by before the …
6. algebra

When a ball is thrown in the air, the height h of a ball in feet t seconds after the ball is thrown in the air, is given by the equation height = 25t–16t² Use the quadratic equation to determine how many seconds goes by before the …
7. math HELP

When a ball is thrown in the air, the height h of a ball in feet t seconds after the ball is thrown in the air, is given by the equation height = 25t–16t² Use the quadratic equation to determine how many seconds goes by before the …
8. math

A ball is thrown into the air with an upward velocity of 20 ft/s. Its height (h) in feet after t seconds is given by the function h(t) = –16t^2 + 20t + 2. How long does it take the ball to reach its maximum height?
9. Algebra

A ball is thrown into the air. The height in feet of the ball can be modeled by the equation h = -16t2 + 20t + 6 where t is the time in seconds, the ball is in the air. When will the ball hit the ground?
10. Algebra

A bottle rocket launches into the air. The equation h=-16t^2+64t+9 gives the height of the ball, h in feet, as a function of t, number of seconds after launch. What is the maximum height the ball reaches?

More Similar Questions