A car travels a distance of 72 km at a certain average speed of x km per hour and then travels a distance of 81 km at an average speed of 6 km per hour more than its original average speed. If it takes 3 hours to complete the total journey then form a quadratic equation and solve it to find its original average speed.
Explanation
The equation is formed by using the formula distance = speed * time. Let's assume the original speed is x km/h. Then the second speed is (x + 6) km/h. The total time taken is 3 hours. So, the equation becomes 72/x + 81/(x + 6) = 3. Cross multiplying and simplifying, we get x^2 - 9x - 513 = 0.
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