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7.8 Approximating Solutions Using Euler’s Method

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.

Euler’s Method is a procedure for approximating a solution to a differential equation or approximating a point on a solution curve when an exact formula is not available. Starting from an initial condition, the method uses the slope given by the differential equation to move forward in small steps. At each step, the slope determines the change in y, and then that new point becomes the starting point for the next step. In AP Calculus, this topic is BC only.

The basic update rule is
yn+1=yn+f(xn,yn)Δxy_{n+1}=y_n+f(x_n,y_n)\Delta x
,
where
f(xn,yn)f(x_n,y_n)
is the slope from the differential equation at the current point and
Δx\Delta x
is the step size. Smaller step sizes usually produce better approximations because the method follows the local slope information more closely. Euler’s Method connects slope fields and numerical approximation, showing how differential equations can be used even when no explicit solution is known.

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