SOLUTION: Imogene's car traveled 336 miles averaging a certain speed. If the car had gone 6 mph faster, the trip would have takes 1 hour less. Find the average speed.

Question 904050: Imogene's car traveled 336 miles averaging a certain speed. If the car had gone 6 mph faster, the trip would have takes 1 hour less. Find the average speed.
Answer by ewatrrr(24785) (Show Source): You can put this solution on YOUR website!
|Multiplying thru by r(r+6) so as all denominators = 1
336(r+7) - 336r = r(r+6)
r^2 + 6r - 2352 = 0 (Tossing out the negative solution for unit measure)

Solved by pluggable solver: SOLVE quadratic equation with variable

Quadratic equation (in our case ) has the following solutons:

For these solutions to exist, the discriminant should not be a negative number.

First, we need to compute the discriminant : .

Discriminant d=9444 is greater than zero. That means that there are two solutions: .

Quadratic expression can be factored:

Again, the answer is: 45.5901224530254, -51.5901224530254. Here's your graph:

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