Question

A missile is fired such that its height above the ground is given by h=-9.8t^2+38.2t+6.5, where t represents the number of seconds since the rocket was fired. Using the quadratic formula, determine, to the nearest tenth of a second, when the rocket will hit the ground.
Please I need help with this question

Answer 1

Answer:

4.1 sec

Step-by-step explanation:

-9.8t^2 +38.2t + 6.5 = 0

t = $\frac{-38.2 +-\sqrt{38.2^2{ - 4(-9.8)(6.5)} } }{2(9.8}$

 =  $\frac{-38.2 +- \sqrt{1459.24 + 254.8} }{-19.6}$

 = $\frac{-38.2 +- \sqrt{1714.04} }{-19.6}$

 = $\frac{-38.2 +- 41.4}{-19.6}$

 = $\frac{-79.6}{-19.6}$

 = 4.1