A ball is thrown from a height of 32 meters with an initial downward velocity of 2 m/s. The ball's height h (in meters) after t seconds is given by the following.h = 32 -21-57How long after the ball is thrown does it hit the ground?Round your answer(s) to the nearest hundredth.(If there is more than one answer, use the "or" button.)

Respuesta :

The given expression is

[tex]h=32-2t-5t^2[/tex]

The ground is at h = 0, so

[tex]0=32-2t-5t^2[/tex]

Now, we use the quadratic formula to find the solutions.

[tex]x=\frac{-b\pm\sqrt[]{b^2-4ac}}{2a}[/tex]

Where a = -5, b = -2, and c = 32.

[tex]\begin{gathered} x=\frac{-(-2)\pm\sqrt[]{(-2)^2-4\cdot(-5)\cdot(32)}}{2\cdot(-5)}=\frac{2\pm\sqrt[]{4+640}}{-10}=\frac{2\pm\sqrt[]{644}}{-10} \\ x=\frac{2\pm25.38}{-10} \\ x_1=\frac{2+25.38}{-10}=-2.7 \\ x_2=\frac{2-25.38}{-10}=2.34 \end{gathered}[/tex]

In this case, just the positive solution makes sense.

Therefore, the ball takes 2.34 seconds to hit the ground.