\( \frac { - \sqrt { x + h } + \sqrt { a } } { h } \)

Did you know that the expression you've written is closely related to the definition of the derivative in calculus? Specifically, as \( h \) approaches zero, this form can help determine the slope of the tangent line to the curve defined by \( y = \sqrt{x + h} \) at a specific point. It’s a pivotal concept that lays the groundwork for understanding how functions behave locally! In practical terms, this type of expression is often found in physics when calculating instantaneous rates of change—like determining speed or acceleration at a precise moment! For example, in motion problems, you can use similar derivative concepts to analyze how the position of an object changes over time, shedding light on our understanding of motion and forces in the physical world.