OCR MEI C3 — Question 7

Exam BoardOCR MEI
ModuleC3 (Core Mathematics 3)
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicImplicit equations and differentiation
TypeFind dy/dx at a point
DifficultyStandard +0.3 This is a straightforward implicit differentiation question with standard techniques: substituting x=2 to find intersection points (solving a quadratic), then applying implicit differentiation formula (2y+1)dy/dx = 3x²+2, and evaluating at given points. Slightly easier than average as it follows a predictable template with no conceptual surprises.
Spec1.02c Simultaneous equations: two variables by elimination and substitution1.07s Parametric and implicit differentiation

Fig. 7 shows the curve defined implicitly by the equation $$y^2 + y = x^3 + 2x,$$ together with the line \(x = 2\). \includegraphics{figure_7} Find the coordinates of the points of intersection of the line and the curve. Find \(\frac{dy}{dx}\) in terms of \(x\) and \(y\). Hence find the gradient of the curve at each of these two points.

Fig. 7 shows the curve defined implicitly by the equation
$$y^2 + y = x^3 + 2x,$$
together with the line $x = 2$.

\includegraphics{figure_7}

Find the coordinates of the points of intersection of the line and the curve.

Find $\frac{dy}{dx}$ in terms of $x$ and $y$. Hence find the gradient of the curve at each of these two points.

\hfill \mbox{\textit{OCR MEI C3  Q7}}