Answer:
t = 0.35, t = 5.65
Step-by-step explanation:
You are given h = 30t - 5t^2. Put this in standard form order (ax^2 + bx + c) by switching the two terms.
h = -5t^2 + 30t
Now you want to find all the values of t for which the rocket's height is 10 meters, so your equation will be equal to 10 instead of h, because 10 is the height you are solving for.
10 = -5t^2 + 30t
Make the entire equation equal to 0 by subtracting 10 from both sides.
0 = -5t^2 + 30t - 10
To solve this quadratic equation, the easiest way would be to use the quadratic formula: [tex]\frac{-b\pm\sqrt{b^2-4ac}}{2a}[/tex]
Identify your a, b, and c values in the standard form equation (a = -5, b = 30, c = -10) and substitute these values into the quadratic formula.[tex]\frac{-(30)\pm\sqrt{(30)^2-4(-5)(-10)} }{2(-5)} \rightarrow \frac{-30\pm\sqrt{900-200=700} }{-10} \rightarrow \frac{-30\pm\sqrt{700} }{-10}[/tex]
We have (-30 ± sqrt 700)/-10.
Use a calculator to input the two solutions and solve for them; (-30 + sqrt 700)/-10 and (-30 - sqrt 700)/-10.
[tex]\frac{-30+\sqrt{700} }{-10} = 0.35[/tex]
[tex]\frac{-30- \sqrt{700} }{-10} =5.65[/tex]
