a) \( x^{2}+2 x \)

Did you know that the expression \( x^{2} + 2x \) can be factored? If you factor it, you get \( x(x + 2) \). This reveals its roots easily; setting \( x(x + 2) = 0 \) gives \( x = 0 \) and \( x = -2 \). These values are where the graph intercepts the x-axis! In practical terms, this expression represents a quadratic function, and its graph is a parabola that opens upwards. You might encounter it in scenarios like physics for projectile motion, where you analyze an object’s height based on time. Knowing how to manipulate such expressions can help you solve various real-world problems efficiently!