Mathematics 9709 · AS & A Level · Differential equations

Differential equations — practice question

(a)[2]

Write $\frac{1}{4 - y^2}$ as a partial fraction expression.

(b)[6]

The variables $x$ and $y$ obey the differential equation $x\frac{dy}{dx} = 4 - y^2$, and $y = 1$ when $x = 1$. Solve the differential equation and obtain $y$ as a function of $x$.

(i)[2]

Decompose $\frac{1}{4 - y^2}$ into partial fractions.

(ii)[6]

The variables $x$ and $y$ obey the differential equation $x\frac{dy}{dx} = 4 - y^2$, and $y = 1$ when $x = 1$. Solve this differential equation to find an expression for $y$ in terms of $x$.

Worked solution & mark scheme

This 16-mark question has a full step-by-step worked solution and mark scheme. One marking point: Use an appropriate method to determine $A$ and $B$ so that $\frac{1}{4-y^2}=\frac{A}{2+y}+\frac{B}{2-y}$

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