1.8: Past-paper question 11

4PM1/1/June/2023 — Question 11 · 14 marks

f(x)=10+6xx2f(x) = 10 + 6x - x^2
Given that f(x)\displaystyle f(x) can be written in the form A(x+B)2+C\displaystyle A(x + B)^2 + C where A\displaystyle A, B\displaystyle B and C\displaystyle C are constants,
(a) find the value of A\displaystyle A, the value of B\displaystyle B and the value of C\displaystyle C
(4)
(b) Hence, or otherwise, find
(i) the value of x\displaystyle x for which f(x)\displaystyle f(x) has its greatest value
(ii) the greatest value of f(x)\displaystyle f(x)
(2)
The curve C\displaystyle C has equation y=f(x)\displaystyle y = f(x)
The curve S\displaystyle S with equation y=x2x+13\displaystyle y = x^2 - x + 13 intersects curve C\displaystyle C at two points.
(c) Find the x\displaystyle x coordinate of each of these two points.
(3)
(d) Use algebraic integration to find the exact area of the finite region bounded by the curve C\displaystyle C and the curve S\displaystyle S.
(5)