Multiple choice general knowledge math & puzzles First derivative of a parabola is a - straight line inclined at 45 deg to x axis straight line parallel to y axis straight line parallel to x axis straight line Reveal answer Fill a bubble to check yourself D Correct answer Explanation A parabola is defined by a quadratic equation (y = ax^2 + bx + c). Its first derivative is a linear equation (y' = 2ax + b). A linear equation graphically represents a straight line.