The sketch displays a section of the curve with equation $y = x^3 - 2bx^2 + b^2x$ together with the line $OA$, and $A$ is the maximum point on the curve. The $x$-coordinate of $A$ is $a$, and the curve also has a minimum point at $(b, 0)$, where $a$ and $b$ are positive constants.
(a)[4]
Show that $b = 3a$ using the information given.
(b)[7]
Show that the shaded region between the line and the curve has area $ka^4$, where $k$ is the fraction to be found.
Worked solution & mark scheme
This 11-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Differentiate to obtain $\frac{dy}{dx}=3x^2-4bx+b^2$” …