Mathematics 9709 · AS & A Level · Differential equations

Differential equations — practice question

The diagram shows a moving point $P$ at $(x, y)$ and the point $N$, which is the foot of the perpendicular from $P$ to the $x$-axis. $P$ lies on a curve for which, whenever $x > 0$, the gradient of the curve is equal to the area of triangle $OPN$, where $O$ is the origin. The point $(0, 2)$ is on the curve.
(a)[1]

State a differential equation linking $x$ and $y$.

(b)[5]

Solve the differential equation to find the equation of the curve, with $y$ written as a function of $x$.

(c)[1]

Sketch the curve clearly.

Worked solution & mark scheme

This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: State the equation $\dfrac{dy}{dx}=\tfrac12xy$

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