A ball is thrown from an initial height of 4 feet with an initial upward velocity of [tex]$29 \, \text{ft/s}$[/tex]. The ball's height [tex]$h$[/tex] (in feet) after [tex]$t$[/tex] seconds is given by the following equation:

[tex]\[ h = 4 + 29t - 16t^2 \][/tex]

Find all values of [tex]$t$[/tex] for which the ball's height is 16 feet. Round your answer(s) to the nearest hundredth.

If there is more than one answer, use the "or" button.

[tex]\[ t = \boxed{} \, \text{seconds} \][/tex]



Answer :

To solve for the values of [tex]\( t \)[/tex] when the ball's height [tex]\( h \)[/tex] is 16 feet, follow these steps:

1. Set the Height Equation Equal to 16:
The height [tex]\( h \)[/tex] as a function of time [tex]\( t \)[/tex] is given by:
[tex]\[ h = 4 + 29t - 16t^2 \][/tex]
Set [tex]\( h \)[/tex] to 16:
[tex]\[ 16 = 4 + 29t - 16t^2 \][/tex]

2. Rearrange the Equation:
Move all terms to one side to set the equation to 0:
[tex]\[ 0 = -16t^2 + 29t + 4 - 16 \][/tex]
Simplify the equation:
[tex]\[ 0 = -16t^2 + 29t - 12 \][/tex]

3. Solve the Quadratic Equation:
This is a standard quadratic equation of the form [tex]\( at^2 + bt + c = 0 \)[/tex], where [tex]\( a = -16 \)[/tex], [tex]\( b = 29 \)[/tex], and [tex]\( c = -12 \)[/tex].

Use the quadratic formula:
[tex]\[ t = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \][/tex]
Substituting in the coefficients:
[tex]\[ t = \frac{-29 \pm \sqrt{29^2 - 4(-16)(-12)}}{2(-16)} \][/tex]
Simplifying inside the square root:
[tex]\[ t = \frac{-29 \pm \sqrt{841 - 768}}{-32} \][/tex]
Further simplifying the square root:
[tex]\[ t = \frac{-29 \pm \sqrt{73}}{-32} \][/tex]

4. Calculate the Two Possible Values of [tex]\( t \)[/tex]:
Solving for the two values of [tex]\( t \)[/tex]:
[tex]\[ t_1 = \frac{-29 + \sqrt{73}}{-32} \][/tex]
and
[tex]\[ t_2 = \frac{-29 - \sqrt{73}}{-32} \][/tex]

5. Determine the Numerical Values:
Calculate the values to the nearest hundredth:
[tex]\[ t_1 \approx 0.64 \][/tex]
[tex]\[ t_2 \approx 1.17 \][/tex]

So, the values of [tex]\( t \)[/tex] when the ball's height is 16 feet are:
[tex]\[ t = 0.64 \text{ seconds or } t = 1.17 \text{ seconds} \][/tex]