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7.3 Sketching Slope Fields

Part of Differential Equations in AP® Calculus BC. Read the opening section, then create a free account for the full interactive lesson, practice, and progress tracking.

A slope field is a graphical representation of a first-order differential equation. At many points in the plane, a small line segment is drawn whose slope matches the value of the derivative at that point. So if the differential equation is
dydx=f(x,y)\frac{dy}{dx}=f(x,y)
,
then each small segment in the slope field has slope f(x,y) at its location. A slope field does not give one exact solution immediately, but it gives visual information about the behavior of entire families of solutions.

To sketch a slope field, students evaluate the derivative expression at selected points and draw short segments with the appropriate slopes. If the slope is 0, the segment is horizontal. If the slope is positive, it tilts upward; if negative, it tilts downward. Steeper values produce steeper segments. Patterns matter a lot: if the differential equation depends only on x, then slopes repeat in vertical columns; if it depends only on y, they repeat in horizontal rows. This helps students sketch slope fields efficiently and recognize structure.

The image below represents the slope field of dy/dx = 2x/y

Note: ON THE AP EXAM YOU WILL ONLY HAVE TO DRAW SLOPES FOR CERTAIN POINTS WHICH ARE PROVIDED ON THE FRQ SECTION!

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