Multiple choice Which of the following equations is a quadratic equation? 7x2 - 7x3 - 7x2 + 5 = 0 14x3 - 12x + 8x2 + 2 = 0 7x2 - 14x3 + 2x + 3 = 0 x2 - 3x3 + 2x + 3x3 = 0 Reveal answer Fill a bubble to check yourself D Correct answer Explanation A quadratic equation has highest power 2 after simplifying. In option D, the cubic terms cancel, leaving x^2 + 2x + 3 = 0, which is quadratic.