An extraneous solution is a solution that's not really a solution. In other words, you work out the problem and you obtain a solution. Then you test your solution by plugging in your solution to the formula given, if the result is false then it's considered an extraneous solution.
For example, if you're solving for time it took for a football to reach the ground after somebody threw it, you would obtain two answers for time. These time answers are negative time and positive time, well the negative time makes no sense since it's before you threw the ball so we would consider that negative solution to be extraneous.
In this equation y represents the total gallons of water in the pool the 500 represents the water that goes into the pool in an hour. X represents the number of hours and 3000 represents the water that was already in there.
If this is a right triangle, then the sum of the squares of the two shorter sides will equal the square of the longest side: 7^2 + 9^2 = 11^2 => 49 + 81 = 121 But this is false.
