what is the last number that represent c is an odd number, what do i do?

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that really doesn't matter. You'll still have to move your C to the other side to get the x values alone. Then you complete the square by adding that certain value you find to complete the square to both sides. Now you can take the square root of both sides. Be careful: if you end up with the square root of a negative value, then that is no real solutions(for now).