# The fuel of a rocket is launched is given by #-x^2 - 140x +2000#. During what period of time is the mass of the fuel greater than 500t?

##### 1 Answer

Jun 19, 2018

The time period is:

#### Explanation:

I am assuming that the function gives the weight of the fuel (in tons) and that the time variable

Please observe that at

Let's find the time where the weight of the fuel is

Factor:

Discard the negative root:

The time period is: