## Intermediate Algebra (6th Edition)

We know that: $$0 = -16t^2 +20t+550$$ Note, we subtract 550 since we want to find when the object is 550 feet off of the ground. Next, we find: $$x= \frac{-b \pm \sqrt{b^2-4ac}}{2a}$$ Where b is the coefficient of the term with a variable raised to the first power, a is the coefficient of the squared term, and c is the coefficient of the term without a variable in front of it. Plugging in the given values and solving, we get: 6.5 s